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

Annotations already flag destructive=true, idempotent=false, openWorld=true. The description adds genuinely new behavioral context: 'Fields left out stay' (partial-update semantics, important given the destructive hint) and the one-time disclosure that the forwarding key 'comes back once, as forward_secret'. It stops short of stating reversibility, permissions, or rate limits.

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?

Front-loaded with the purpose, then a compact enumeration of the writable fields and the key side effect. It is dense but every clause carries information; no filler or repetition.

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 7-parameter, nested-object mutation with no output schema, the description covers the main payload shape, patch semantics, and the one-time secret return. passport_token and rotate_forward_secret are left to the schema, which documents them well, so nothing critical is missing.

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 description coverage is 100%, so the schema already documents every parameter including enums and the hmac-only 'header' detail. The description adds only light clarifiers ('same address', null turns a feature off) and no syntax or format detail beyond the schema, 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 ('Set') and resource ('webhook inbox pro plan'), then enumerates the exact configuration domains it writes (forward, verify, handshakes). This is clearly distinguishable from the sibling inbox_pro_get (read vs. write), though it never names the sibling explicitly.

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 phrase 'Fields left out stay' conveys patch-style update semantics, which is useful context, but there is no explicit when-to-use/when-not guidance and no reference to the read counterpart (inbox_pro_get) or to related inbox tools. Usage is only implied by the verb and field list.

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