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

The readOnlyHint annotation already signals a safe read operation, and the description adds behavioral context by stating 'Returns exact + full-text matches' and clarifying the search scope. It does not contradict annotations and offers useful extra information about match behavior, going beyond what annotations provide.

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 concise, with three short sentences that each add key information: purpose, match behavior, and REST endpoint. No fluff or repetition, and it is front-loaded with the primary action.

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?

Although no output schema exists, the description gives a hint about return behavior ('Returns exact + full-text matches'), implying a list of matching members. For a simple search tool with well-documented parameters and annotations, this is adequate, but a more explicit description of the return structure would elevate it to a 5.

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 100% with both parameters described. The description adds value by specifying what the query can contain ('email, name or other fields') and clarifying that list_id restricts to 'one audience'. This enriches the schema descriptions, earning a 4.

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 clearly states a specific verb ('Search') and resource ('members'), with scope ('across the account or one audience') and searchable fields ('email, name or other fields'). This distinguishes it from sibling tools like mailchimp_list_members (listing all) and mailchimp_get_member (fetching by ID).

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 when to use: searching members by arbitrary fields across the entire account or a specific audience. It does not explicitly name alternatives or exclusions, but the context of searching by email/name/other fields clearly differentiates it from listing or getting members. The lack of explicit alternative naming prevents a 5.

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