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

The description adds transparency beyond annotations by explaining idempotency ('Clearing a flag that is not set changes nothing and is not an error'), batch behavior, and the non-destructive nature of the operation. It does not contradict the annotations (readOnlyHint false, idempotentHint true, 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?

The description is verbose and repetitive (e.g., 'one call' mentioned multiple times, long warnings about care and verification). While informative, it could be trimmed significantly without losing meaning.

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?

The description covers all necessary context: batch operation, idempotency, mailbox handling, and edge cases like unset flags. It fully equips the agent to use the tool correctly without ambiguity.

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 descriptions for both parameters are thorough: uids includes usage, limits, and examples, while mailbox explains its default. This covers all parameters with 100% schema coverage.

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's purpose: 'Clear the flag/star marker on messages, restoring their unflagged state.' It specifies the verb (clear), the resource (emails), and distinguishes it from sibling tools like flag_email and mark_unread.

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 provides explicit usage guidance: 'Pass the whole set in ONE call' with rationale, instructs to 'Clear the ones you were asked about and no others,' and explains the mailbox parameter. It also clarifies verification and default behavior.

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