forward-message

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

With no annotations, the description carries the full burden of behavioral disclosure. It prominently warns that default send=true sends real email immediately, cannot be unsent, and requires explicit user confirmation—or recommends send=false for review. It also states the return value, covering key side effects and safety.

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 well-organized with labeled sections (Use when, Do not use when, Returns, Safety). Every sentence serves a purpose, front-loaded with the primary use case, and no unnecessary verbosity.

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 potentially irreversible send operation, the description covers usage, alternatives, return value, safety, and key parameter semantics. The output schema exists, so return details are not burdensome. This is a complete and self-contained description.

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 50% (id and to lack descriptions), but the description compensates by clarifying 'to is an array', 'by id', and the purpose of the prepended body. It doesn't explain how to obtain id, but the schema provides a pattern and sibling tools imply the source. This adds meaningful value over the schema.

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 action: forwarding an existing message by id to new recipients, with an optional prepended body. It also distinguishes from sibling tools like reply-to-message and send-email/create-draft, making the tool's unique purpose unmistakable.

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 explicitly provides 'Use when' and 'Do not use when' sections, naming alternative tools (reply-to-message, send-email, create-draft) and specifying the condition 'forwarding an existing message'. This is exemplary usage guidance.

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