email_reply

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

No annotations are provided, so the description carries the full burden. It does state that it replies to an EXISTING email, which distinguishes from creating a new send. However, it doesn't mention side effects (sending immediately vs draft), whether a 'confirmed' confirmation or idempotencyKey is needed for safe mutation, or what happens to attachments/threads. For a mutation tool with zero annotation coverage, this is a modest disclosure but not rich.

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 a single efficient sentence with no wasted words. It is appropriately front-loaded and concise, though this brevity comes at the cost of missing important nuance about parameters and usage.

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?

With 6 parameters, 0% schema coverage, no output schema, no annotations, and a mutation operation, the tool is under-documented. The description is too thin to fully inform the agent about the confirmed/idempotencyKey gating mechanism, body format requirements, or replyAll semantics. Given the complexity and absence of structured support, it should carry more explanatory weight.

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 description coverage is 0%, so the description must compensate for the 6 parameters. It adds no meaning beyond what the schema shows: it doesn't clarify what 'body' accepts structurally (text vs html), what replyAll does, what confirmed gates, or what idempotencyKey is for. The description adds zero parameter insight when it should be carrying a significant burden.

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 'Reply to an existing email' uses a clear verb+resource structure that identifies the core action. However, it doesn't distinguish itself from siblings like email_forward, email_send, or email_draft_create, which are adjacent email-creation operations.

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?

There is no guidance on when to use this tool vs email_send or email_forward. It doesn't explain account setup prerequisites (e.g., needing to add an account first via email_add_account) or whether replyAll parameter exists to switch modes. No exclusions or alternative tool references are provided.

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