mail_set_flag_color

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

Annotations already indicate this is a mutation (readOnlyHint=false), idempotent, non-destructive. Description adds that -1 clears the flag. However, it does not disclose return behavior, authentication needs, or side effects (e.g., whether existing flag is replaced). With idempotentHint=true, the description is adequate but lacks depth.

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?

Single sentence, no waste. Front-loaded with verb and resource. Could potentially add a brief note on parameter identification without sacrificing conciseness.

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?

Tool has 5 parameters (3 required), no output schema. Description only covers one parameter's semantics. For a mutation tool, more context is needed on how the flag is identified (via messageId or rfc822MessageId) and the effect of setting an existing flag. Insufficient for effective invocation.

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 0%, meaning the description must explain parameters. It partially explains colorIndex (range and -1 meaning) but says nothing about messageId, accountName, mailboxPath, or rfc822MessageId. For required parameters, the description omits critical identification details.

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?

Description uses specific verb 'Set' and resource 'colored-flag index', clearly distinguishing from sibling 'mail_set_flagged' which likely toggles a boolean flag. The range and clearing behavior are specified.

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?

Implicitly describes usage by explaining -1 clears and 0-6 selects colors, but does not explicitly state when to use this tool vs alternatives like mail_set_flagged or mail_set_read_status. No when-not-to-use or prerequisites mentioned.

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