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

The annotations already declare readOnlyHint=true and openWorldHint=true, so safety behavior is covered. The description adds useful return-content context by saying results include unique and total clicks, but it does not disclose pagination behavior, permissions, or error handling.

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?

A single sentence with no filler, front-loading the resource and the key returned metrics. It is appropriately sized for a simple read-only listing operation.

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?

The tool is a simple read-only listing operation; annotations cover safety, and the schema fully documents parameters including pagination. The description names the returned metrics but does not describe the return structure or distinguish this tool from related mailing-summary tools.

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 100%, and all three parameters are documented in the schema, including defaults and pagination guidance for start and limit. The description adds no additional parameter meaning beyond what the schema already provides, so the baseline of 3 applies.

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 resource (links of one mailing) and the returned metrics (unique and total clicks). It is specific enough to identify the operation, but it does not explicitly differentiate this tool from siblings such as emma_list_mailing_activity or emma_get_mailing_response.

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 explicit guidance on when to use this tool versus alternatives, nor any mention of exclusions. The phrase 'of one mailing' implies the required mailing context, but an agent must infer when this is the right choice over related mailing tools.

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