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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds context about return behavior ('Returns directive errors to fix and revalidate') and establishes this tool as a gate for execution. This goes beyond annotations without conflicting with them.

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 with no redundant wording. The purpose is front-loaded, and the second sentence efficiently conveys return behavior and the validity constraint.

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?

Given a single well-documented parameter, output schema, and clear annotations, the description sufficiently covers purpose, usage context, and return behavior. It is complete for the tool's complexity.

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?

The schema provides a full description for the 'plan' parameter, referencing generation_plan_brief's planJsonSchema. The tool description adds no additional parameter-specific semantics, but with 100% schema coverage, a baseline of 3 is appropriate.

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 clearly states the tool's function: validating a generation plan against the schema and model capabilities. It uses a specific verb ('validate') and resource ('generation plan'), and the phrase 'before execution' distinguishes it from planning or execution tools like generation_plan_brief.

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?

The description implies when to use this tool: after authoring a plan and before execution. It does not explicitly name alternatives or exclusions, but the context is clear enough from 'self-authored' and 'only a valid plan is executable.'

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