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

Annotations already cover write/idempotent/non-destructive/non-open-world semantics, and the description adds real context beyond them: authorization role requirement, plan gating with the exact failure mode, and a note on the return value (project costs). It stops short of explaining what happens to a budget when it is cleared, which is the only notable gap.

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?

Three short sentences, front-loaded with the action, then qualifications, then the return value. No padding or redundancy.

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 3-parameter mutation with no output schema, the description covers permissions, plan gating, mutation behavior, and the return payload. Only the effect of clearing the budget on existing costs is left unaddressed.

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% and every parameter is already documented, including the omit-to-clear semantics for budget. The description merely restates that currency and budget are what's being set, adding no format or validation detail beyond the schema's 'three-letter currency code' note.

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 (project's currency and budget) in the first sentence, which is enough to distinguish it from the general update_project sibling. It does not explicitly contrast with update_project, which limits it to a 4.

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 clear preconditions: must be Administrator or ProjectManager, and must be on a Pro plan (Free workspaces get a plan-limit message). This tells the agent when the call will succeed, but it never names update_project as the general-purpose alternative or says when to use which.

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