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

No annotations are provided, so the description must carry the full burden. It discloses that the tool returns a summary with specific data points and hints at a plan requirement, but does not elaborate on whether it's read-only (obvious from context), authentication requirements, or potential rate limits. The disclosure is adequate for a simple get operation but lacks depth.

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, clear sentence that conveys the tool's purpose and a usage note (plan feature) in parentheses. No unnecessary words, and the key information is front-loaded.

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 has no output schema and simple parameters, the description provides a reasonable overview of what the response contains (reputation, domain auth, bounce/complaint health). It also mentions a plan restriction. It could be improved by specifying the return format or error conditions, but for a get tool, it is fairly complete.

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%, as the single parameter 'apiKey' is documented in the schema. The tool description does not add any additional meaning beyond the schema. Baseline of 3 is appropriate.

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 tool retrieves the workspace's deliverability summary including sending reputation, domain authentication, and bounce/complaint health. The verb 'get' and resource 'deliverability summary' are specific, and the sibling tools list shows no other deliverability-specific tool, distinguishing it effectively.

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 retrieving deliverability status, and notes it's a 'Deliverability Hub plan feature' which provides a precondition. However, it does not explicitly state when to use versus alternatives or mention any exclusions, which would elevate it to a 5.

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