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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, and the description adds valuable behavior beyond these: it is served from cache, cheap to call, includes a freshness stamp, and behaves differently without a key by returning a withKey block. This gives an agent a realistic expectation of cost, freshness, and auth-dependent output.

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 a single dense, information-rich sentence with no filler. Every clause adds meaningful guidance: cache-backed, cheap, specific metrics, board-vs-employer disambiguation, freshness stamp, and keyless behavior. The key facts are front-loaded and the length is appropriate for the content.

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 zero-parameter tool with an output schema available, the description is complete. It covers the data scope, the source and cost profile, the keyless mode, and the presence of a freshness stamp. There are no missing prerequisites, inputs, or behavioral caveats that an agent would need to invoke this tool correctly.

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?

The tool has zero parameters and the schema confirms this, so parameter semantics are trivially complete. The description does not need to explain any parameter meaning and does not attempt to. A baseline of 4 is appropriate for a parameterless tool.

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 uses a specific verb with a clear resource: 'Live board statistics from cache' and enumerates exactly what is included (posting totals, board counts, category set, freshness stamp). It also disambiguates 'boards, not employers' to prevent a common misinterpretation. This clearly distinguishes board_stats from the sibling employer-oriented stats tools.

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 gives practical usage context: it is 'cheap to call' and serves data from cache, implying it is appropriate for quick or repeated statistics lookups. It also clarifies that it 'answers with no key too,' which helps an agent know it works without authentication. It does not explicitly name alternative tools or exclusion conditions, but for a zero-parameter read-only stats tool this is sufficiently clear.

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