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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds value the annotations cannot: results are limited to the caller's memberships, and the ids returned are the foreign key for every sibling tool. It stops short of describing the shape of each returned site record.

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?

Two short sentences, zero filler. The sequencing instruction is front-loaded as the second sentence, which is the highest-value information for an agent deciding what to call first.

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 entry-point tool with no output schema, the description conveys what it returns (site ids) and how to use them downstream, which is the critical missing piece an agent would otherwise have to discover by trial. It does not enumerate other fields on a site record, a minor gap given there is no output schema to cover it.

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 takes zero parameters, so there is no parameter semantics to compensate for; the baseline for a 0-param tool is 4. The description correctly implies no filtering input is needed, though it does not explicitly say the call is unfiltered.

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 Anry sites') with a clear scope qualifier ('the authenticated user is a member of'). The scope qualifier alone separates it from siblings like list_sessions or list_reports, which are narrower resource listings.

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?

Gives an explicit sequencing instruction ('Call this first') plus the reason ('every other tool takes one of these site ids as site_id'). That is a when-to-use rule and a dependency explanation in one sentence, leaving nothing to infer.

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