reply_email

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

Discloses rate limit and default behavior for subject/recipient. With no annotations, it partially covers behavioral traits but omits other important aspects like whether it sends immediately or modifies original email.

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, no redundancy. Each sentence provides essential information: purpose and constraints/defaults.

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 8 parameters, no output schema, and no annotations, the description is too brief to provide complete context. Lacks details on return value, side effects, and how attachments work.

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?

With 0% schema description coverage, the description only adds meaning for 'subject' and 'to' via defaulting behavior. Other parameters (cc, bcc, bodyText, etc.) are not explained, leaving the agent to infer their purpose solely from names.

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?

Clearly states 'Reply to an existing thread.' The verb 'Reply' and resource 'existing thread' specify the action and scope. Distinguishes from sibling send_email which creates new threads.

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?

Explicitly says it replies to an existing thread and mentions rate limit of 5/min, guiding usage. However, it does not explicitly state when not to use or mention alternatives.

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