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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful context beyond that: what the results contain (participants, read status) and that results are cursor-paginated. It does not, however, note rate limits or auth requirements.

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 compact sentences that front-load the resource and scope, then parameters, then pagination. The trailing endpoint reference ('Hostfully: GET /api/v3.3/threads') is mild implementation trivia but does not bloat the definition.

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 simple read-only list tool with no output schema, the description covers scope, pagination, and the gist of returned fields. An agent has enough to invoke it, though the lack of tie-breaking guidance against hostfully_list_messages leaves a small gap.

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 75%, so most parameters are self-documented. The description adds only marginal meaning, noting the lead_uid/agency_uid scoping choice and the default fallback; limit and cursor are left entirely to the schema.

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 guest-messaging threads') with scope ('for an agency or one lead') and return content ('participants and read status'). It is clear, though it does not explicitly differentiate itself from the sibling hostfully_list_messages.

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?

'Give lead_uid, or agency_uid (or the default)' implies how to scope the call but never states when to choose this over alternatives like hostfully_list_messages or how to pick between the lead_uid and agency_uid paths. Usage is implied rather than spelled out.

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