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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds value beyond that: it scopes the data source ("from the results 442ball holds"), the temporal windows (longest this season and since 2010), and explicitly sets output granularity with "Run lengths only" – preempting an agent from expecting match lists.

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 front-loaded sentences: what is returned, its scope, and the output limit, then the input dependency last. No restatement of the title and no filler.

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?

For a read-only single-parameter tool with no output schema, the description covers return content, data source, time windows, and input provenance. Minor gaps remain: it does not say what happens for an unknown slug or whether a club with no runs returns empty values.

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 description coverage is 0%, so the description must carry the parameter. It does the most useful thing possible: names the parameter's source (the slug from resolve) and by implication its form, compensating for the bare pattern-only schema. It stops short of documenting the slug pattern or error behavior, so not 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?

States a specific verb and resource ("Returns one club's current and longest runs"), then enumerates the exact run types: unbeaten, winning, winless, clean sheets, overall/home/away. The qualifier "one club's" implicitly separates it from the sibling league_runs, so an agent can route correctly without opening either 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?

"Takes the club slug from resolve" gives an explicit prerequisite and points to the exact sibling tool that produces the input, which is the critical usage instruction here. It does not state when to prefer league_runs or compare_clubs instead, so it falls short of full when/when-not guidance.

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