Reply

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

Annotations already indicate the tool modifies state (readOnlyHint=false) and is not destructive. The description adds 'threading preserved' but does not disclose other behaviors (e.g., whether original email is flagged, sent folder behavior).

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 with no waste, but could benefit from a slightly more detailed explanation of threading preservation.

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?

Five parameters and no output schema; description is too minimal. It does not explain 'threading preserved' in practical terms, nor does it mention reply construction conventions (subject prefix, attachments).

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 80%, meaning most parameters have descriptions. The tool description adds no extra parameter meaning beyond the schema. Baseline score of 3 is appropriate.

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 'Reply to the sender of an email, threading preserved,' which identifies the specific action and resource. It also implicitly distinguishes from 'email_reply_all' by limiting to the original sender.

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?

No guidance on when to use this tool versus alternatives like 'email_reply_all' or 'email_send.' Lacks exclusions or conditions for use.

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