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

With readOnlyHint and openWorldHint already present, the description adds value by specifying the return content (parsed body, verification codes, confirmation links) and disclosing the per-call price. It does not contradict the annotations, and its additional details are honest and useful.

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?

Three short sentences, with the operative behavior first, usage guidance second, and cost last. There is no filler or redundant restatement of the title.

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 one-parameter read operation with read-only annotations and no output schema, the description covers the id source, return value, usage context, and cost. It could mention behavior for nonexistent ids, but that is a minor omission for this level of complexity.

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?

The schema exposes only a generic id string, and schema description coverage is 0%. The description compensates by stating that the id comes from inbox.list, which gives the parameter concrete origin and meaning. A sample or format would strengthen it further, but the essential semantic is present.

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 opens with 'Return the full parsed body of one message, plus any verification code or confirmation link found in it,' a specific verb-resource pair that clearly distinguishes reading a single message from listing the inbox. It also references the sibling inbox.list, reinforcing the conceptual separation.

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?

An explicit 'When to use' section tells the agent to call with an id from inbox.list whenever full text or a link is needed. It gives clear contextual conditions, though it does not spell out when not to use the tool or name alternatives.

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