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

Annotations already declare destructiveHint=true, openWorldHint=true and idempotentHint=false, so the description adds the valuable rate-limit constraint (3 forwards per hour per workspace) and the default-vs-headers behavior. It does not explain what makes the operation destructive (e.g., new delivery created, original untouched), which is a real gap for a destructive mutation.

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 tight sentences: purpose first, then the mode toggle, then the rate limit. Every sentence carries information an agent needs, with no redundancy against the schema.

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 destructive, non-idempotent 9-parameter tool with no output schema, the description covers the key mode toggle and rate limit but leaves several parameters and the destructive semantics (attachment handling, whether the original is modified, response shape) unaddressed.

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 56%, so roughly half the parameters are undocumented anywhere. The description adds meaning for include_headers and comment (including the body alias only indirectly), but 'from', 'subject', 'html', and 'text' go unexplained, and 'to'/'id' are left to 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?

States a specific verb and resource ('Forward an outgoing email to a new recipient') and clarifies the default mode versus the include_headers variant. It doesn't explicitly distinguish itself from send-email or retry-email, so sibling differentiation is only implied.

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?

Explains the default behavior (plain resend) and when to use include_headers, which is useful conditional guidance. However, it never names alternatives such as send-email, retry-email, or update-email, nor does it state when not to forward.

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