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

Annotations only carry readOnlyHint=true, so the description carries the behavioral burden and delivers richly: the case-insensitive substring behavior, the 'every row of a matching fixture is returned' behavior spanning live and prematch markets, the ~20-row window scope, and the critical caveat that an empty answer does not prove the fixture is off the board. No contradiction with the readOnly annotation.

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 description is front-loaded with purpose and examples, then usage, then scope caveat, then exclusions. It is dense but information-rich, and every sentence adds behavioral or routing value. Slightly long, but the length is justified by the tool's non-obvious window limitation and empty-result semantics.

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 present, the description compensates by explaining the return behavior (all markets, live and prematch) and the window limitation. It covers the main agent-facing risks (empty result meaning, not an ID lookup). It could specify the exact output field structure, but for a search tool the behavioral expectations are well covered.

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%, so both parameters are already documented in the schema, giving a baseline of 3. The description adds marginal value through examples illustrating the name parameter's substring semantics, but it does not substantially extend what the schema already states for either parameter.

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 opens with a specific verb and resource — 'Find tape rows by fixture name' — and immediately defines the exact matching semantics (case-insensitive substring) with two concrete examples. It then names what the tool is not (fixture-id lookup, schedule/results source, bet-placement service), distinguishing it from its siblings without needing their schemas.

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 explicit when-to-use guidance ('Use it when the user names a match or a player rather than a sport') and explicit negative exclusions. It stops short of naming the specific sibling that should handle sport-level queries (e.g., get_live_fixtures or get_prematch_fixtures), which would make the routing fully explicit, but the usage context is clear.

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