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

With only readOnlyHint=true in annotations, the description adds real value: it discloses the server-side requirement (a failure mode the agent would otherwise hit) and the paginated return shape. It does not cover auth/permission needs or item-shape details, but the requirement disclosure is the important behavioral fact.

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?

Three short sentences: purpose first, then the hard constraint, then the response envelope. No filler, and the most operationally important fact (the required filter) is front-loaded.

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 9-parameter tool with a nested passthrough object and no output schema, the description compensates well by stating the return envelope (items, count, limit, offset, next_page_url). It stops short of explaining the `params` escape hatch or the from/to arrival-vs-departure semantics, which the agent must infer.

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 the schema already documents every parameter including the q/created_since_utc requirement. The description restates that constraint but adds no syntax, defaults, or meaning beyond the schema, 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+resource ('List guests (contacts)') and even maps it to the underlying endpoint (GET /v2/guests), which lets an agent distinguish it from get_guest and the other list_* siblings 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?

The NOTE gives the decisive prerequisite for calling this endpoint at all: either `q` or `created_since_utc` must be supplied. That is genuinely useful routing/precondition guidance, though it does not explicitly say when to prefer this over get_guest or sibling list tools.

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