cm_get_subscriber

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

The description adds modest context by mentioning 'state and custom fields' as return content, which goes beyond the readOnlyHint annotation. However, it does not disclose any additional behavioral traits such as rate limits, authentication requirements, or data freshness. The annotation already signals safe read-only operation, so the description is adequate but not exceptional.

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 a single concise sentence of 10 words that leads with the verb and resource. Every word contributes meaning, and there is no fluff or repetition. It efficiently communicates the tool's core function.

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?

Given the tool's simplicity (3 parameters, read-only, no output schema), the description is largely complete. It specifies key return fields (state, custom fields). However, since there is no output schema, a brief mention of other typical fields (e.g., name, email) could improve completeness. Overall, it provides sufficient context for an AI agent to understand the tool's role.

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?

Since the input schema has 100% description coverage (each parameter explained), the baseline score is 3. The tool description does not add any parameter-specific information beyond what the schema provides. It does not explain parameter relationships, dependencies, or formatting details.

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 the verb 'Get' and the resource 'subscriber's details', specifying key fields like 'state and custom fields'. It distinctively identifies the tool as retrieving a single subscriber's full details, differentiating it from sibling tools like cm_get_active_subscribers or cm_get_subscriber_history.

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 provides no guidance on when to use this tool versus alternatives. For example, it does not mention that this is for retrieving a single subscriber by email and listId, while for lists of subscribers one should use cm_get_active_subscribers or similar. No when-not or exclusion criteria are given.

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