mark_email

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

The description reinforces the idempotency declared in annotations and adds detail about what constitutes a no-op. It does not contradict annotations. It could mention side effects (e.g., no destructive actions), but annotations already cover destructiveHint=false.

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 that front-load the core purpose and add a key behavioral note. Every word is necessary; no filler.

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 simple flag mutation tool with good annotations and full parameter descriptions, the description is complete. No output schema is needed for such a straightforward operation.

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?

All 4 parameters are fully described in the schema (100% coverage). The description adds minor clarification (e.g., 'flag (star)') but does not provide substantial new meaning beyond the schema definitions.

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 (change) and resource (email flags) and specifies the four possible actions: read, unread, flag, unflag. This distinguishes it from sibling tools like move_email or delete_email.

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 when to use the tool (to change flags) but does not explicitly state when not to use it or compare it with alternatives like send_email or delete_email. The idempotent note is behavioral, not a usage guideline.

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