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

With no annotations, the description carries the burden and does well: it discloses the exact categories of checks and mentions that suggestions are returned. It does not explicitly state that the operation is read-only or non-mutating, but 'Check' strongly implies no side effects, and the level of detail is strong for a validator.

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?

The description is a single, front-loaded sentence that lists the checks efficiently and ends with a clear usage directive. Every clause earns its place with no 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?

Given the low complexity, high schema coverage, and absence of an output schema, the description is nearly complete: it covers the checks performed and notes suggestions. It could add a brief note about the return shape (e.g., list of issues) to be fully self-contained.

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 the single 'html' parameter is fully documented in the schema. The description adds no parameter-specific meaning beyond what the schema already provides, so the baseline of 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?

The description states a specific verb ('Check') and resource ('HTML' / 'MIAN markup'), then enumerates exactly what is validated: unknown mn- classes, noodle ids, data-mn attributes, asset paths, missing stylesheet/script, and hard-coded colours. This clearly distinguishes it from all sibling tools, which are retrieval, listing, or planning tools.

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 instruction 'Run before finishing' provides clear timing context for when to use the tool. However, it does not name alternatives or explicitly state when not to use it, so it falls short of a full 5.

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