forward

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

Annotations declare destructiveHint=false and openWorldHint=true, so the external-side-effect profile is already partly covered; the description still adds real value by warning that sending is user-visible and should be confirmed first and that the original attachments ride along. It does not describe failure modes or what the call returns.

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?

Three short sentences, front-loading the forward-plus-original-attachments behavior, then the comment-placement options, then the safety instruction. Nothing is redundant.

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 mutation tool with no output schema, the description covers the essential behaviors: original attachments included, where comments land, and the confirmation requirement. Missing only return-value expectations and whether forwardText and htmlBody can be combined.

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 86%, so the baseline is 3; the description only restates the forwardText/htmlBody distinction already spelled out in the schema and adds nothing for messageId, the required parameter, or the 25MB attachment constraint. Marginal value over structured fields.

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?

States a specific verb and resource ("Forwards a message") plus a distinguishing scope fact: original attachments are carried along, which separates it from send_message and reply. It never names those siblings explicitly, so the differentiation is inferred rather than stated.

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 sentence "Confirm with the user before sending" gives a clear operational guardrail for when this fires, and the verb implies forward-an-existing-message. But there is no explicit routing versus reply, send_message, or create_draft, which are all plausible alternatives for the same intent.

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