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

Annotations supply destructiveHint=true, so the agent already knows this mutates state. The description adds the useful constraint that the override is scoped to a single identifier, but it does not say whether an existing override is overwritten (vs. only created), whether the call is idempotent, or what authorization/namespace existence is required.

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?

A single front-loaded sentence that captures the operation and its scope with no wasted clauses. The trailing 'Unkey: POST /v2/ratelimit.setOverride.' restates the name/verb and is largely redundant, which keeps it short of a 5.

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?

All four required parameters are covered by the schema and the description establishes scope, so the core is complete. However, with no output schema and only a destructiveHint annotation, the description leaves return behavior and the create-vs-overwrite semantics unstated, which matters for a mutation tool.

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% — limit ('requests allowed per window'), duration ('window length in milliseconds'), namespace, and identifier are all documented in the schema. The description adds no syntax, unit, or constraint detail beyond what the schema already provides, so the 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?

The description states a specific verb and resource (set a custom rate limit) and scopes it precisely to 'one identifier in a namespace', which distinguishes it from namespace-wide or per-key operations. It does not explicitly name the adjacent siblings (get_ratelimit_override, list_ratelimit_overrides), so the differentiation is implicit rather than stated.

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?

'How you raise or lower a single customer's limit' gives a use case, but there is no when/when-not guidance and no mention of checking an existing override first (get_ratelimit_override) or listing overrides. Usage is only implied by the scope wording.

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