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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds useful context: the GET endpoint, that it does not remove opt-outs or send messages, and a security warning about untrusted customer content. The warning about 'message text' is slightly mismatched because the described return is phone numbers and dates, but it is not a contradiction.

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?

The description is short and front-loaded, leading with the core read operation and optional filter. The final untrusted-content sentence is brief but somewhat tangential to a tool returning phone numbers and dates.

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 three optional parameters and no output schema, the description covers the core operation, optional filter, non-mutating behavior, and return content. It stops short of describing pagination metadata or response shape, but most call-critical context is present.

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 the description must compensate. 'Read a page' implies pagination for limit/offset, and 'filter by numeric phone number' explains phoneNumber as a numeric filter, but the description does not add defaults, constraints, or detailed pagination semantics beyond the schema's type and range fields.

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?

The description states a specific verb and resource: 'Read a page of opted-out phone numbers and dates.' It also clarifies the optional phone-number filter and explicitly says it does not remove opt-outs or send messages, which distinguishes it from mutation-oriented tools.

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 for reviewing opt-outs and rules out removal/sending, but it does not name alternatives or state explicit when-to-use conditions versus sibling list/get tools. The guidance is adequate but leaves routing to the agent.

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