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

Annotations already declare destructiveHint, idempotentHint and readOnlyHint=false, so the bar is lower. The description still adds genuine behavioral context beyond the annotations by disclosing the consequence of exceeding the cap (those emails are skipped for the contact) and the disable path via null — consistent with, not contradicting, destructiveHint=true.

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 tight sentences with the core behavior front-loaded and no filler. The phrasing 'Set the most marketing emails' is slightly garbled (should read 'maximum number of'), which costs a little readability but not length.

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 setter with no output schema and annotations that cover the safety profile, the description supplies what an agent needs: parameter semantics, the disable value, and the downstream effect. Only the duration of the 'rolling window' and the scope of 'marketing emails' remain undefined, which slightly limits completeness.

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 0%, so the description must carry the load, and it does for the important semantics: null turns the cap off, which the schema's type union does not explain. The '1 to 50' range merely restates the schema's min/max, so it adds no extra value, keeping this just short of a 5.

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 (frequency cap) plus the exact scope it governs: the number of marketing emails a single contact receives within a rolling window. The added effect clause ('emails over the cap are skipped for that contact') makes the purpose unmistakable, and no sibling tool competes for this function.

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 only implied: an agent can infer this is the tool to call when it wants to limit marketing email volume, but the description never states when to reach for it or whether any precondition (e.g. plan, workspace-level setting) applies. No alternative tool is named because none exists, so the gap is minor but real.

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