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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description's real contribution is elsewhere: it discloses that small crowds return an empty board, that drafts and closed sites are excluded from ranking, and that no key is needed. That is genuine behavioral context beyond the annotations, though it stops short of anything about result ordering or freshness beyond 'latest score'.

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?

Labeled sections (When, Instead, Inputs, Returns, Fails) make it scannable, and the purpose sentence is front-loaded. Every line carries distinct information with no restatement of the name or title.

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?

Seven optional parameters, two enums, and no output schema, yet the description covers filtering, the record variant, paging, the returned fields (total, offset, limit, sites, tiers, note), and failure modes. Nothing an agent needs in order to call this correctly 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 baseline is 3, but the description earns more: it explains that the filters combine 'together or alone', that city requires state, that record substitutes a single record for the place list, and that limit/offset page the board. These are interaction rules the schema does not state.

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 ('Lists the public leaderboard') plus the three shapes it can take: all ranked sites, one crowd's board, or a single record. The 'Instead' line explicitly separates it from clickd_site and clickd_rivals, so an agent can route without opening a 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?

An explicit 'When' clause gives the triggering intent ('show a person where a site places among every site, or sites like it') and an 'Instead' clause names both alternatives with the condition that selects them. No inference required.

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