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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld, so the safety profile is covered. The description adds genuinely new context: it is a 'Free-tier endpoint' and it defines the temporal window (3 days back to 30 days ahead) and the shape of each returned object.

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

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

Front-loads the free-tier tag and resource, then the window, then the field list. The sentence is dense with an inline field enumeration, but every element (window, id systems, books) earns its place given there is no output schema.

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

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

No output schema exists, and the description compensates well by naming the fields returned (PropLine id, commence_time, espn_event_id, mlb_game_pk, merged_from_event_ids, per-book ids/links). Pagination and response envelope details are absent, keeping it just under a 5.

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

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

Schema coverage is 100% and there is a single param, so the schema already carries the meaning. The description only adds that the crosswalk is scoped to 'one sport', which lightly reinforces sport_key but adds no format or enumeration detail. Baseline 3 is appropriate.

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

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

States a specific resource (id crosswalk) with explicit scope (one sport) and enumerates the returned fields, including the alternate id systems. It does not name or distinguish itself from the nearby sibling propline_list_events, so it falls short of a 5.

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

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

The 'Useful for' clause gives concrete when-to-use scenarios (joining PropLine events onto ESPN/MLB Stats API/a sportsbook feed, mapping DraftKings ids). It provides clear context but no explicit exclusions or named alternatives, so it is a 4 rather than a 5.

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