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

Beyond the annotations' read-only, idempotent, non-destructive profile, the description discloses free-tier status, any-date coverage, batch limit of 50 comma-separated ids, miss behavior via not_found, and returned fields including crosswalk, status, completed flag, and final score. These are meaningful behavioral details an agent would not get from the annotations alone.

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?

The definition is front-loaded with the endpoint tier and reverse-lookup purpose, then quickly covers accepted ids, return contents, date scope, batching, miss handling, and examples. Every sentence adds useful information, and the examples are short enough to aid selection without bloating the description.

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?

With no output schema, the description carries the return-value burden and does so by naming the crosswalk, status, completed flag, and final score. It also covers the important call-shape constraints: accepted id families, any date, batch size, and not_found behavior. Nothing essential for correct invocation is missing.

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 only 50%, but the description compensates by explaining the three lookup modes: book plus book_event_id, ESPN event id, and MLB gamePk. It also clarifies that book_event_id can be comma-separated up to 50 ids. It leaves some ambiguity about whether multiple id modes can be combined in one call, which keeps it from a 5.

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?

The description states a specific reverse-lookup verb and resource: given a book, ESPN, or MLB id, return PropLine's event with its id crosswalk. The phrase 'reverse id lookup' and the named id domains distinguish it from forward listing or event-detail siblings. An agent can tell what this tool is for without opening the schema.

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?

It gives concrete usage contexts such as 'what was the result of Pinnacle event 1612345678' and 'which PropLine event is this ESPN game', which makes the when-to-use case clear. It does not explicitly compare against sibling tools like propline_get_event_ids or propline_list_events, so it stops short of full alternative routing.

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