Set the render FPS cap (sUNC setfpscap)

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

Adds genuinely useful behavior beyond annotations: type-guarding, pcall wrapping, the exact error payload for a missing setfpscap, the return shape { cap, ok }/{ error }, and prerequisites. However, it declares 'idempotency=idempotent-write' while the annotations set idempotentHint=false, a direct conflict that misleads an agent deciding whether retrying is safe.

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-loads the most important fact ('WRITES CLIENT STATE') and is organized into scannable clauses. It is somewhat bloated with metadata boilerplate (Phase, cost, Produces, Verify with) that dilutes the key guidance, but each part is on-task.

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?

With no output schema, the description correctly documents return values and error cases, states prerequisites and a verification path, and warns that the operation is mutating. Only the internal idempotency inconsistency and missing guidance on unsetting/restoring state leave a small gap.

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 the schema already documents cap/timeoutMs/threadContext. The description restates the signature and reinforces the 0=uncapped rule (already in the schema) but adds no new syntax or constraints, 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?

States a specific verb (set) and resource (render FPS cap) plus the underlying primitive setfpscap(cap), and says explicitly it writes client state. It is immediately distinguishable from the sibling get-fps-cap (read) and from unrelated executors/setters.

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?

Gives concrete call context: 'Pass 0 to uncap the frame rate', 'Requires setfpscap', plus gates (active-client, explicit-mutation-approval) and a verification step (assert-state). It does not name alternatives or when NOT to use it, so it stops short of a 5.

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