sendGmailEmail

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

With no annotations, the description carries full responsibility for behavioral disclosure. It states the tool sends an email (a mutation) and can reply to a thread, which are essential behaviors. However, it does not mention authentication requirements, potential side effects (e.g., sending emails is irreversible), or error handling. The description adds some value but lacks richer behavioral context expected for a mutating tool without annotations.

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 two concise sentences, front-loaded with the primary action ('Sends an email directly...') and then the optional reply capability. No wasted words; every sentence contributes useful information.

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 tool that sends an email, the description covers the core purpose and the main optional behavior (reply). With 100% schema parameter coverage and a straightforward action, the description is mostly complete. It lacks information about return values (no output schema) and error cases, but these are less critical for a send operation. The description could mention prerequisites like Gmail authentication, but overall it is sufficient for the tool's complexity.

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 input schema provides 100% coverage with descriptive parameter comments for all 7 parameters, so the description doesn't need to explain them. The description's mention of replying to a thread adds mild context but does not go beyond what the schema already documents for threadId and inReplyTo. Baseline 3 is appropriate since the schema handles parameter semantics thoroughly.

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 function: 'Sends an email directly through the user's Gmail account.' It also mentions the optional reply-to-thread capability, which differentiates it from sibling tools like saveGmailDraft (which saves rather than sends) and other Gmail read/list tools.

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 clear context: this tool sends an email immediately, versus saving a draft or performing other Gmail operations. It doesn't explicitly name alternatives (e.g., 'use saveGmailDraft to save without sending'), but the phrase 'directly through the user's Gmail account' implies a send action. The reply capability is also mentioned, giving a specific use case.

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