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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds the backing endpoint (GET /sites) but omits whether the three filters combine with AND or OR semantics, whether an empty filter returns everything, and whether results are paginated.

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 with the resource and filters front-loaded. The trailing 'API: GET /sites' is marginally useful for endpoint mapping but is close to padding.

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 list tool with all params documented and annotations covering safety, this is nearly sufficient. However, with no output schema, the description should hint at the returned shape or pagination/limit behavior, which it does not.

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 100%, so each of the three parameters is already documented in the schema. The description paraphrases the same filters without adding semantics such as mutual exclusivity or precedence between uid, email, and address, so baseline 3 applies.

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 (List) and resource (property sites), plus the filtering dimensions. It is clearly distinguishable from get_site (single-site retrieval) by the plural resource and filter framing, though it never names a sibling.

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 implies usage by listing the available filters, but never says when to prefer this over get_site or list_users, nor whether the filters are required or combinable. Usage must be inferred from the schema's optional parameters.

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