League Loom

Get Available Players (Free Agents / Waivers)

fantasy_get_available_players

Read-onlyIdempotent

Browse players you can ADD in ONE league (free agents + waivers), best first: THE waiver/pickup tool. Excludes rostered players: for a specific named player use fantasy_get_player_data; for waiver ideas across ALL leagues at once, fantasy_get_weekly_digest has a top add per league. ESPN: % owned, season + projected points. Sleeper: every player not rostered, by relevance rank. Fantrax: points, ownership and ADP in viewable leagues or with a saved session cookie, else an ADP-backed fallback.

Input Schema

Name	Required	Description	Default
`sort`	No	Ranking key. Default: best available first (ESPN: % owned; Sleeper: relevance rank).
`limit`	No	Max players.
`query`	No	Player-name substring.
`sport`	No	e.g. 'NFL', 'NBA'. Needed for ESPN/Sleeper and Fantrax name lookups.
`season`	No	Season year, e.g. 2025; ignored by Fantrax.
`position`	No	Position code, e.g. 'RB', 'PG'.
`provider`	No	Fantasy platform. Optional: defaults to your connected platform ('sleeper').
`league_id`	No	Omit when connected. League id (Fantrax also takes the league URL).
`credentials`	No	Only WITHOUT a connected profile: secret_id (Fantrax), espn_s2 + swid (private ESPN), username or user_id (Sleeper discovery). Public ESPN and Sleeper reads need none.
`league_query`	No	A connected league's name/id; omit to auto-pick (primary first). Never ask for ids.
`response_format`	No	'markdown' (default, most compact) or 'json' (same normalized data, not the raw payload).	markdown

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 24, 2026

changedInput schema / properties / credentials / additionalProperties
```
Previous value: -trueNew value: +{}
```

changedInput schema / properties / season / anyOf

Previous value: -[
-  {
-    "type": "integer"
-  },
-  {
-    "type": "string"
-  }
-]New value: +[
+  {
+    "maximum": 9007199254740991,
+    "minimum": -9007199254740991,
+    "type": "integer"
+  },
+  {
+    "type": "string"
+  }
+]

Changed9 schema fields changedSep 29, 2026

changedInput schema / properties / credentials / description

Previous value: -"Per-call credentials, only needed WITHOUT a connected profile. Keys: secret_id (Fantrax); espn_s2 + swid (private ESPN leagues); username or user_id (Sleeper discovery); session_cookie / auth_token + write_enabled:true (explicit write opt-in only). Public ESPN leagues and all Sleeper reads need none."New value: +"Only WITHOUT a connected profile: secret_id (Fantrax), espn_s2 + swid (private ESPN), username or user_id (Sleeper discovery). Public ESPN and Sleeper reads need none."

changedInput schema / properties / league_id / description

Previous value: -"The platform's league id (Fantrax also accepts the full league URL)."New value: +"Omit when connected. League id (Fantrax also takes the league URL)."

changedInput schema / properties / league_query / description

Previous value: -"League name/id filter, for when the profile has several leagues on the provider."New value: +"A connected league's name/id; omit to auto-pick (primary first). Never ask for ids."

changedInput schema / properties / limit / description

Previous value: -"Max players to return (1-200)."New value: +"Max players."

changedInput schema / properties / position / description

Previous value: -"Filter to a position code, e.g. 'RB', 'WR', 'PG'."New value: +"Position code, e.g. 'RB', 'PG'."

changedInput schema / properties / query / description

Previous value: -"Optional player-name substring filter."New value: +"Player-name substring."

changedInput schema / properties / response_format / description

Previous value: -"'markdown' (default) or 'json' (raw payload)."New value: +"'markdown' (default, most compact) or 'json' (same normalized data, not the raw payload)."

changedInput schema / properties / season / description

Previous value: -"Season year, e.g. 2025. Required for ESPN/Sleeper league discovery; ignored by Fantrax."New value: +"Season year, e.g. 2025; ignored by Fantrax."

changedInput schema / properties / sport / description

Previous value: -"Sport, e.g. 'NFL', 'NBA', 'MLB', 'NHL'. Required for ESPN/Sleeper and Fantrax name lookups."New value: +"e.g. 'NFL', 'NBA'. Needed for ESPN/Sleeper and Fantrax name lookups."

Changed14 schema fields changedSep 10, 2026

changedInput schema / properties / credentials / additionalProperties
```
Previous value: -falseNew value: +true
```

changedInput schema / properties / credentials / description

Previous value: -"Per-call credentials. Fill only the keys your provider needs (see fantasy_list_providers). Public ESPN leagues and all Sleeper reads need none."New value: +"Per-call credentials, only needed WITHOUT a connected profile. Keys: secret_id (Fantrax); espn_s2 + swid (private ESPN leagues); username or user_id (Sleeper discovery); session_cookie / auth_token + write_enabled:true (explicit write opt-in only). Public ESPN leagues and all Sleeper reads need none."

removedInput schema / properties / credentials / properties / espn_s2

Removed value: -{
-  "description": "ESPN private-league cookie 'espn_s2' (DevTools → Application → Cookies → espn.com).",
-  "type": "string"
-}

removedInput schema / properties / credentials / properties / secret_id

Removed value: -{
-  "description": "Fantrax Secret ID (User Profile → 'Your Secret ID').",
-  "type": "string"
-}

removedInput schema / properties / credentials / properties / swid

Removed value: -{
-  "description": "ESPN private-league cookie 'SWID': a GUID in curly braces, e.g. {XXXX-...}.",
-  "type": "string"
-}

removedInput schema / properties / credentials / properties / user_id

Removed value: -{
-  "description": "Sleeper numeric user_id (alternative to username).",
-  "type": "string"
-}

removedInput schema / properties / credentials / properties / username

Removed value: -{
-  "description": "Sleeper username (for league discovery).",
-  "type": "string"
-}

changedInput schema / properties / league_id / description

Previous value: -"The league id from the platform. For Fantrax, a full league URL is also accepted and the server extracts the id."New value: +"The platform's league id (Fantrax also accepts the full league URL)."

changedInput schema / properties / league_query / description

Previous value: -"Optional profile league name/id filter. Use when the profile has multiple leagues for the provider."New value: +"League name/id filter, for when the profile has several leagues on the provider."

changedInput schema / properties / provider / description

Previous value: -"Fantasy platform: 'fantrax', 'espn', or 'sleeper'. Call fantasy_list_providers first to see each provider's capabilities and required credentials."New value: +"Fantasy platform. Optional: defaults to your connected platform ('sleeper')."

changedInput schema / properties / response_format / description

Previous value: -"Output format: 'markdown' (default, human-readable) or 'json' (raw upstream payload)."New value: +"'markdown' (default) or 'json' (raw payload)."

changedInput schema / properties / season / description

Previous value: -"Season year, e.g. 2024. REQUIRED for espn and sleeper league discovery; ignored by fantrax."New value: +"Season year, e.g. 2025. Required for ESPN/Sleeper league discovery; ignored by Fantrax."

changedInput schema / properties / sport / description

Previous value: -"Sport, e.g. 'NFL', 'NBA', 'MLB', 'NHL'. Required for ESPN/Sleeper and for Fantrax player/name lookups."New value: +"Sport, e.g. 'NFL', 'NBA', 'MLB', 'NHL'. Required for ESPN/Sleeper and Fantrax name lookups."

removedInput schema / required
```
Removed value: -[
-  "provider"
-]
```

First observedJun 29, 2026

TDQS

A4.3/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real behavioral context beyond them: provider-specific result semantics (ESPN % owned, Sleeper every unrostered player by relevance), and importantly the Fantrax session-cookie requirement with an 'ADP-backed fallback' when absent. It stops short of pagination or result-shape detail, so not a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core purpose and exclusions, and each sentence carries routing or provider information. The all-caps emphasis and dense provider clause make it slightly noisy, but nothing is truly wasted.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For an 11-parameter, zero-required tool with no output schema, the description covers what fields come back per provider and when credentials are needed, which is the main ambiguity. Return formatting details are left to the response_format parameter description, a minor gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so every parameter is already documented in-schema; that sets the baseline at 3. The description only echoes a couple of default-sort behaviors per provider, which the schema's sort description largely covers, so it adds little parameter meaning beyond structured data.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Browse players you can ADD'), scopes it to ONE league, and names what is excluded (rostered players). It also explicitly distinguishes itself from siblings, calling itself 'THE waiver/pickup tool' while routing named-player and cross-league cases elsewhere.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Names two alternatives with the exact condition that selects each: fantasy_get_player_data for a specific named player, fantasy_get_weekly_digest for waiver ideas across ALL leagues. The when-to-use boundary is unambiguous.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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