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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the conditional behavior (selecting a mailbox to include folders) and notes that only 'permitted' mailboxes are returned, enriching the behavioral picture without contradicting annotations.

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?

Two sentences with no filler. The core purpose is front-loaded, and the conditional behavior is stated in a compact second sentence. Every word earns its place.

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 output schema and annotations, the description is sufficiently complete for a read-only discovery tool. Pagination and parameter specifics are in the schema, and the conditional folder selection is clearly communicated. Minor terms like 'readiness' are left to the output schema, which is acceptable.

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%, so each parameter is already documented. The description ties mailboxId and includeFolders together in the conditional, but does not add details beyond what the schema's conditional logic already expresses. Baseline 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 uses a specific verb ('Get') and resource ('permitted mailboxes, sending addresses and capabilities'), clearly differentiating it from sibling tools like send_email or search_messages. The second sentence adds the conditional folder selection, making the tool's purpose unmistakable.

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?

It implies usage as a discovery tool for mail context, but does not explicitly state when to use it over siblings or when not to. No alternatives are named, so the agent must infer its role from context.

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