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

Annotations already declare readOnlyHint, destructiveHint false and openWorldHint false, and the description is consistent with them, adding real value by enumerating the sandbox surface (plan.floors, plan.elements, plan.get, plan.describe, plan.warnings, plan.check, plan.search) and the accepted check() argument strings. It stops short of disclosing execution limits, timeouts, or what happens when a script errors, so it is strong but not complete.

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 sentences, front-loaded with the selection criterion before the detail, and the whitelist of available APIs earns its space because it exists nowhere else. The phrase 'returns what it returns' is vague filler and the check() clause is dense, 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?

There is no output schema, yet the description covers the essentials an agent needs: read-only scope, the script dialect's origin, the exact callable surface, and the regulatory check strings. Given only two parameters with no nested objects, remaining unknowns (error handling, rate limits) are marginal rather than blocking.

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 50%: project_id is documented in the schema, but 'script' has no schema description at all. The description compensates well by explaining what a script may reference and which plan.* calls are legal, effectively documenting the opaque parameter's contract; it still does not describe script return/evaluation semantics precisely.

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 ('Runs a read-only script', 'Query plan') and positions it directly against two siblings: describe_plan for standard questions and edit_project for the script dialect. An agent can distinguish this from every other sibling without opening a schema.

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?

It gives an explicit selection rule: use this for questions describe_plan does not answer, implying the converse (use describe_plan when it suffices) and pointing at edit_project for the mutation counterpart. That is when-to-use plus alternatives, which is the top of the scale.

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