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

Annotations already declare readOnlyHint and destructiveHint, and the description adds meaningful behavior beyond those: deterministic execution, purely local work, no AI assistance, no invented fixes, and a 256 KiB input cap. It also pre-states the output categories, so the agent knows what to expect.

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 sentences, all information-dense, with the primary purpose first followed by the return contract and constraints. There is no filler, no repetition of the schema, and every sentence earns its place.

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 parameter and an existing output schema, the description covers purpose, accepted input forms, size limit, validation scope, and result fields. Nothing an agent needs to select or invoke the tool correctly is missing.

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 already documents `uef` as an object or JSON string, and the description reinforces this while adding the 256 KiB cap for both forms. It also explains what the document is validated against, adding context beyond the schema's generic 'UEF document' phrasing.

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 opens with a specific verb and resource — 'Validate a UEF document' — and narrows the scope to 'public EVENT-focused rules,' naming required fields and the return contract. This clearly distinguishes it from siblings like analyze_event_to_uef and get_uef_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 implies usage through 'Deterministic local workbook — no AI, no org write, no invented fixes,' which signals a safe, side-effect-free validation context. However, it does not explicitly state when to prefer this tool over alternatives or when not to use it, leaving some routing to inference.

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