mark_email

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

Annotations already declare idempotentHint=true, but the description adds specific behavioral context by explaining that marking an already-read email as read is a no-op. This goes beyond structured data and clarifies the idempotency semantics.

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 short sentences with no filler, front-loading the action and adding only the useful idempotency detail. 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?

For a simple flag mutation tool with full schema coverage and idempotency annotations, the description covers all essential information. No output schema exists, and return values are not needed for this 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?

Schema coverage is 100%, with each parameter described in detail including the action enum. The description's mention of 'read/unread, flag/unflag' mirrors the schema's action values without adding new parameter semantics, so the baseline score 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 changes email flags (read/unread, flag/unflag), which is a specific verb+resource combination. It distinguishes itself from sibling tools like move_email or delete_email by focusing solely on flag modifications.

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 makes it obvious when to use this tool—whenever email flags need to be modified. It doesn't explicitly mention alternatives or exclusion criteria, but the tool's narrow scope makes misuse unlikely and no alternative flag tool exists among siblings.

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