Set email preferences

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

Annotations only declare idempotentHint, so the description carries most of the burden and does add real behavior: partial-update semantics ('omitted topics stay as they are') and a scope boundary that essential mail (password reset, verification) is unaffected. It also discloses the return shape, which no output schema provides; the main gap is that it doesn't say how to discover which optional topics exist.

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 core action and the partial-update rule, and every clause (ready meaning, unaffected essential mail, return shape) carries information. The parenthetical about Settings → Account is slightly tangential and the sentence fragments make it a bit choppy, but nothing is padding.

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 one-parameter, idempotent mutation with no output schema, the description covers what changes, what is preserved, what is out of scope, and the return shape — enough to call it correctly. The remaining hole is discoverability of topics and the read counterpart, which the description never mentions.

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% for the single parameter, and the description's 'ready = the note sent when projects finish while you are away' essentially restates the schema's own definition rather than adding new meaning. With one well-documented parameter, baseline 3 is appropriate.

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 gives a specific verb and resource: turning optional-email topics on or off, with a clear scope restriction that only optional mail is touched. It never names the sibling get_email_preferences, so the read/write pairing with that tool must be inferred from the name alone.

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?

Usage is implied rather than stated: call it to toggle a topic, and omitted topics are left untouched (useful partial-update guidance). It offers no explicit when-to-use or when-not guidance and never points at get_email_preferences for reading current state, though the Settings → Account remark hints at where this is surfaced.

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