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

Annotations already declare readOnlyHint and destructiveHint=false, so the description does not need to re-argue safety. It does add real behavioral detail: unspecified last_message objects and custom field values are omitted from the response, results are single-page, and message text is flagged as untrusted customer content — a security note no annotation conveys.

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?

Four short declarative sentences, front-loaded with the returned payload before the endpoint, omission caveats, and security note. Nothing is redundant and every sentence carries information an agent cannot get from the schema or annotations.

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 two-parameter read tool with annotations covering the safety profile and no output schema, the description covers returned fields, omission behavior, pagination, and trust concerns well. The main gap is that no return structure is described at all, so an agent cannot anticipate the response shape.

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 0%, so both parameters are undocumented in structured form. The embedded path template 'GET /dashboards/{dashboard_id}/contacts/{phone_number}' does map each parameter to its role, but neither the phone-number format expectation (the schema regex is uncommented) nor dashboard_id's meaning is explained in prose.

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 ('Read') and resource ('contact'), and enumerates what is returned: context, group/tag membership, opt-out timestamp. It is distinguishable from list_contacts by being a single-resource fetch, though it never names the sibling to make the split explicit.

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?

There is no statement of when to use this versus textrequest_list_contacts or textrequest_list_contact_messages. The only contextual hints are the endpoint path and 'Returns one page unless stated otherwise', which imply a single-contact lookup but give no exclusions, prerequisites, or alternatives.

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