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

Annotations already provide readOnly, idempotent, and non-destructive hints. The description adds valuable behavioral nuance: the stats are computed from records rather than manually maintained, matches without loaded results are counted separately instead of as draws, and the tool merges recent matches with the full archive. This goes beyond the annotations without contradicting them.

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?

Three sentences with no waste: first sentence defines purpose and result summary, second reveals behavioral caveats, third explains data source and provides a parameter example. Purpose is front-loaded and each sentence earns its place.

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?

Given the simple read-only nature, annotations covering safety, and 75% schema parameter coverage, the description is complete. It explains what the tool returns, how missing results are handled, how historical and recent data are combined, and when to use the rivalry parameter. No critical information appears 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 covers 75% of parameters with descriptions. The description repeats the rivalry example 'superclasico', which is already present in the schema, and adds no new semantic information for limit, sport, or opponent. The description neither compensates for nor worsens the schema coverage.

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 clearly states the tool returns River Plate's head-to-head history against a specific rival, including games played, wins, draws, losses, and goals. This distinguishes it from generic match-listing tools, though it does not explicitly name a sibling tool for contrast.

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 description implies usage when an agent needs historical aggregate stats against an opponent, and it gives a concrete example for using the rivalry parameter. However, it never explicitly states when to prefer this tool over siblings like get_matches or get_match_report, nor does it mention any exclusions.

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