imap_reply_to_email

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

With no annotations, the description carries the behavioral burden and does well: it discloses automatic recipient selection, subject prefixing, threading headers, replyAll expansion, and default BCC injection. It does not state permission/auth requirements or immediate-send side effects, but the key reply behavior is clearly described.

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 compact and front-loaded: purpose first, then automatic behavior, then replyAll, then sibling routing, then BCC behavior. Every sentence adds distinct information without duplication.

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 10-parameter mutation tool with no annotations and no output schema, the description covers the critical reply mechanics and alternatives well. It omits return/confirmation details and broader error handling, but remains sufficient for correct 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 100%, so the baseline is 3, but the description adds meaning beyond the schema by explaining that folder + uid identify the original message, how replyAll affects recipients, and that defaultBcc is always merged. It does not cover every parameter (e.g., attachment semantics), but the added reply-specific context is valuable.

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 states a specific verb and resource: reply to an existing email, identified by folder + uid. It also explicitly distinguishes this from imap_send_email, so the agent can select the right sibling without opening either schema.

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?

It gives an explicit when-to-use rule: use this instead of imap_send_email whenever the user is responding to a message already in a mailbox. It also clarifies the replyAll condition and defaultBcc behavior, leaving little ambiguity about selection.

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