GridIron Data

Find a player by ESPN id

get_player_by_espn_id

Read-onlyIdempotent

Returns the player whose ESPN athlete id this is (the numeric id ESPN and many sportsbook feeds use), as the same record get_player returns. Use it to join ESPN or sportsbook data to GridIron player ids. Free plan.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "espn_id": "<espn_id>"
    },
    "name": "get_player_by_espn_id"
  }
}

Input Schema

Name	Required	Description	Default
`espn_id`	Yes	ESPN athlete id (numeric).

Output Schema

Name	Required	Description
`ids`	No	Other systems' ids from the nflverse crosswalk.
`note`	No	A sentence for the user saying which plan is needed.
`team`	No	Current team code.
`error`	No	Present only when the call failed: what went wrong.
`reason`	No	Machine-readable failure reason, e.g. basic_required or pro_required.
`status`	No	HTTP status of the failed API call.
`position`	No	Position.
`player_id`	No	GridIron player id ("First Last#POS").
`player_name`	No	Player name.
`upgrade_url`	No	Where to see the plans.
`required_plan`	No	The plan that unlocks this data: basic or pro.
`espn_player_id`	No	ESPN athlete id.

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 10, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already cover read-only, idempotent, closed-world, non-destructive semantics, so the bar is lower. The description still adds real context beyond them: the returned record is identical to get_player's, and the endpoint is on the "Free plan," which hints at tier/billing behavior. It stops short of saying what happens for an unknown ESPN id.

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

Conciseness5/5

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

Two tight sentences, front-loaded with the identity and return shape, followed by the practical join use case. No filler, no restatement of the title, and the plan note is a short trailing clause.

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?

With an output schema present, return values need no explanation, and the single required parameter is fully documented. Purpose, identifier provenance, and usage are all covered; the only gap is lookup-failure behavior (unknown or malformed ESPN id), which matters for an id-keyed fetch.

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

Parameters4/5

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

Schema coverage is 100% (the single espn_id param is documented as "ESPN athlete id (numeric)" with an example), so the baseline is 3. The description earns above baseline by explaining where such ids come from (ESPN and many sportsbook feeds), telling an agent what to supply when it holds sportsbook-sourced identifiers.

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 ("Returns the player whose ESPN athlete id this is") and immediately disambiguates the identifier as the numeric ESPN/sportsbook id, versus the sibling get_player and get_player_by_gsis_id. It also pins the return shape as "the same record get_player returns," so an agent knows exactly what it gets without opening a schema.

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

Usage Guidelines4/5

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

"Use it to join ESPN or sportsbook data to GridIron player ids" gives a concrete when-to-use condition tied to the input's provenance. It does not explicitly name get_player_by_gsis_id as the alternative for GSIS-keyed data, but the id-type framing makes the choice inferable.

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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