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

Annotations already declare destructiveHint=true, readOnlyHint=false and openWorldHint=true, so safety profile is covered. The description adds a genuinely useful constraint – attachments are unsupported and file paths cause an error – but says nothing about irreversibility of sending or how scheduling affects delivery.

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?

Two short sentences, front-loaded with the action and followed by the key operational caveat. No filler, though it spends its second sentence on a constraint the schema already repeats.

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?

An output schema exists, so return values need not be described, and annotations carry the safety profile. However, for a 10-parameter mutation tool with scheduling and timezone options, the description leaves the forward-vs-reply decision and delivery timing behavior unexplained.

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 all 10 parameters are already documented in the schema, including defaults for email/content and tzMode. The description adds only the attachments caveat, which the schema itself also states, so baseline 3 applies.

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 email to another recipient'), which clearly separates it from mutating siblings like update_lead or archive_contact. It doesn't explicitly distinguish itself from send_reply, the closest sibling, but the action is unambiguous.

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 forward versus send_reply, no mention of prerequisites (sender connectivity, workspace selection), and no exclusions. The only constraint given is about attachments, which is a limitation rather than usage guidance.

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