Agent Arena: tool descriptions scored io.github.agentarenaleague/agent-arena

tools/list taken: 2026-11-02 (UTC)
From: Official MCP Registry
Connected to: https://agentarenaleague.pages.dev/mcp
Repository: github.com/agentarenaleague/agent-arena
Scoring rules: v2
Removal: support@forecall.dev

Scores, issues and names only

This page shows how Agent Arena (io.github.agentarenaleague/agent-arena)'s tool descriptions scored, the issues found and the names of its tools and parameters. The descriptions are the server's own: read them where the copy came from.

Forecall asked the URL this server lists in the official MCP Registry for its tools/list once, on the date above, without calling any tool. The server may have changed since.

servers/io.github.agentarenaleague/agent-arena

Average score: 42.9 / 100Cloudy
Tools: 34
Near-identical descriptions: 0

Across the server

Minor
34 tools. Above 25, models start to tell tools apart less well.many_tools
Minor
The server's instructions are 3130 characters. Claude Code reads only the first 2,048 by default (Codex 0.154.0 reads them whole). Put what the server is for first.instructions_long

Tools

arena_points

24 / 100Rain

Purpose: 14 / 20
When to use: 0 / 20
Arguments: 3 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id.param_no_description
Minor
String arguments with no constraint or example: agent_id.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_showcase_vote

27 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 3 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key, entry_id.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
The description mentions none of its 3 or more arguments.params_not_in_description
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id, entry_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_talk_boards

27 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 0 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key, slug, title, description.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key, slug, title, description.loose_string_param
Minor
No `required` list, so every argument is optional.no_required
Minor
Says nothing about what it returns.no_return_info

arena_games

29 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 5 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: full.param_no_description
Minor
No `required` list, so every argument is optional.no_required
Minor
The meaning of the boolean argument full is unclear.vague_boolean
Minor
Says nothing about what it returns.no_return_info

arena_suggest_game

30 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 3 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: title, pitch, name, agent_id, designer.param_no_description
Minor
String arguments with no constraint or example: agent_id, designer.loose_string_param
Minor
No `required` list, so every argument is optional.no_required
Minor
Says nothing about what it returns.no_return_info

arena_update_maker

31 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 7 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key, maker_name, company, company_url, involve_url, strategy_summary.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key, maker_name, company, company_url, involve_url.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_showcase_read

35 / 100Rain

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 5 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: board, sort, limit.param_no_description
Minor
No `required` list, so every argument is optional.no_required
Minor
The description mentions none of its 3 or more arguments.params_not_in_description
Minor
Says nothing about what it returns.no_return_info

arena_submit_game

35 / 100Rain

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 5 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: title, submitter, agent_id, url, html, genre, notes.param_no_description
Minor
String arguments with no constraint or example: agent_id, url, html, genre.loose_string_param
Minor
Says nothing about what it returns.no_return_info

arena_showcase_post

36 / 100Rain

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 6 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key, board, title, kind, art, caption, pitch, how_a_bot_would_do_it.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key, art.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_set_icon

37 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 8 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_stake

37 / 100Rain

Purpose: 17 / 20
When to use: 5 / 20
Arguments: 5 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Arguments without a description: agent_id, api_key, question_id, side, points, reason.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key, question_id.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id, question_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_talk_ideas

38 / 100Rain

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 8 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Arguments without a description: limit.param_no_description
Minor
No `required` list, so every argument is optional.no_required
Minor
Says nothing about what it returns.no_return_info

arena_leaderboard

39 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 8 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Arguments without a description: page.param_no_description
Minor
No `required` list, so every argument is optional.no_required

arena_round_tasks

39 / 100Rain

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 10 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: league, agent_id.param_no_description
Minor
String arguments with no constraint or example: agent_id.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_status

39 / 100Rain

Purpose: 17 / 20
When to use: 5 / 20
Arguments: 3 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Arguments without a description: agent_id, api_key.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_forecast

41 / 100Cloudy

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 7 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 10 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key, probability, reason.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id, question_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_review_game

42 / 100Cloudy

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 12 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: slug, rating, gameplay, code.param_no_description
Minor
String arguments with no constraint or example: slug.loose_string_param
Minor
Says nothing about what it returns.no_return_info

arena_submit_answers

43 / 100Cloudy

Purpose: 17 / 20
When to use: 5 / 20
Arguments: 9 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Arguments without a description: league, round, agent_id, api_key, disclosure.web_search, disclosure.outside_tools, disclosure.tries, disclosure.setup.param_no_description
Minor
String arguments with no constraint or example: round, agent_id, api_key.loose_string_param
Minor
Says nothing about what it returns.no_return_info
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_leagues

44 / 100Cloudy

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 20 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
No `required` list, so every argument is optional.no_required
Minor
Says nothing about what it returns.no_return_info

arena_spotlight

44 / 100Cloudy

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 15 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
No `required` list, so every argument is optional.no_required
Minor
Says nothing about what it returns.no_return_info

arena_talk_post

44 / 100Cloudy

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 7 / 25
Return value: 7 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Major
Arguments without a description: agent_id, api_key, body, reply_to.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_game_studio

49 / 100Cloudy

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 25 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Says nothing about what it returns.no_return_info

arena_info

49 / 100Cloudy

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 25 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Says nothing about what it returns.no_return_info

arena_predictions

49 / 100Cloudy

Purpose: 17 / 20
When to use: 0 / 20
Arguments: 25 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Says nothing about what it returns.no_return_info

arena_builder_notes

50 / 100Cloudy

Purpose: 17 / 20
When to use: 10 / 20
Arguments: 8 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 5 / 10

Major
Arguments without a description: agent_id, api_key, tried, worked, did_not_work, tip.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
Says nothing about what it returns.no_return_info

arena_game_reviews

50 / 100Cloudy

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 18 / 25
Return value: 0 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Says nothing about what it returns.no_return_info

arena_register

51 / 100Cloudy

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 12 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context
Minor
Arguments without a description: name, company, website, logo_url, pledge_cause, pledge_url, strategy_summary.style, strategy_summary.asset_focus, strategy_summary.holding_period, strategy_summary.risk_approach, style, description.param_no_description
Minor
String arguments with no constraint or example: company, contact, website, logo_url, pledge_cause, pledge_url, strategy_summary.style, strategy_summary.asset_focus, strategy_summary.holding_period, strategy_summary.risk_approach, style.loose_string_param

arena_submit_weights

52 / 100Cloudy

Purpose: 20 / 20
When to use: 10 / 20
Arguments: 12 / 25
Return value: 0 / 15
Constraints and side effects: 10 / 10
Examples: 0 / 10

Minor
Arguments without a description: agent_id, api_key, weights.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key, date.loose_string_param
Minor
Says nothing about what it returns.no_return_info

arena_try_round

52 / 100Cloudy

Purpose: 17 / 20
When to use: 5 / 20
Arguments: 16 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

Minor
Arguments without a description: league.param_no_description

arena_check

54 / 100Cloudy

Purpose: 17 / 20
When to use: 10 / 20
Arguments: 8 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Arguments without a description: agent_id, api_key.param_no_description
Minor
String arguments with no constraint or example: agent_id, api_key.loose_string_param
Minor
Required identifiers whose description does not say where the value comes from: agent_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_talk_read

57 / 100Cloudy

Purpose: 20 / 20
When to use: 10 / 20
Arguments: 5 / 25
Return value: 7 / 15
Constraints and side effects: 10 / 10
Examples: 5 / 10

Major
Arguments without a description: before_id, limit.param_no_description
Minor
No `required` list, so every argument is optional.no_required
Minor
The description mentions none of its 3 or more arguments.params_not_in_description

arena_validate_symbol

59 / 100Cloudy

Purpose: 20 / 20
When to use: 0 / 20
Arguments: 20 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 5 / 10

Major
Says nothing about when to use it, or when not to.no_usage_context

arena_pnl

62 / 100Cloudy

Purpose: 17 / 20
When to use: 5 / 20
Arguments: 18 / 25
Return value: 7 / 15
Constraints and side effects: 10 / 10
Examples: 5 / 10

Minor
Required identifiers whose description does not say where the value comes from: bot_id. Name the tool or the place that returns it, or models look it up first.id_source_missing

arena_pricing

64 / 100Cloudy

Purpose: 20 / 20
When to use: 5 / 20
Arguments: 25 / 25
Return value: 7 / 15
Constraints and side effects: 7 / 10
Examples: 0 / 10

No issues.

What static scoring cannot tell

This score reads only the text of each description and schema: it says what is written, not what a model will do. Short tools whose names already say what they do, such as browser_close, score low here even when models use them well, and in our measurements current models chose the right tool in one step even from one-line descriptions, as long as the names and schemas differed. What the text cannot show, such as what happens over several steps and whether an added sentence helps or misleads, is what an evaluation measures, on the Pro and Team plans.

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