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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuine behavior beyond that: a 20-row result cap, the scan_capped flag and its follow-up, and the guarantee that it will not fabricate an unpublished ranking. The 'Read-only' clause is mildly redundant with readOnlyHint but not contradictory.

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?

Four sentences, each carrying distinct information, with the core purpose front-loaded before return shape, follow-up behavior, and safety. Only the trailing 'does not invent a ranking the site does not publish' phrasing is slightly muddy and could be tighter.

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 single-parameter read tool with a full output schema, the description covers everything an agent needs: the identifier format, the row cap, the partial-result escape hatch, and the safety posture. Nothing required for a correct call 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 100%, so the baseline is 3, but the description goes further by giving the full URL pattern and a concrete example slug ('crude-steel-production-by-country'), clarifying the expected format beyond the schema's terse 'Path segment after /rankings/.'

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 ('Read one published country ranking') and pins down the exact access path via the /rankings/{slug} URL template, which is far more specific than the generic siblings fetch and search. An agent can tell immediately that this is the targeted ranking reader rather than a general fetch or search.

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?

Usage is implied by the slug-based lookup, and there is one conditional next step ('If scan_capped is true, open the ranking URL for the complete table'). However, there is no explicit guidance on when to choose this tool over fetch or search, which is the selection decision an agent actually faces.

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