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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds genuine context beyond them: rules are keyed to severities, they are 'read against source', and a clean self-review does not constitute visual approval. It doesn't describe ordering or result size behaviour, which keeps it out of 5 territory.

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?

Four short sentences, front-loaded with what is returned before the usage hint and the parameter note. Nothing is padded, though the 'Pass `category` for one group' sentence earns little since the enum already carries that information.

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, so the description must convey the return shape, and it does: a set of rules tagged by severity across six named categories. Combined with the caveat about source-based evaluation, an agent has enough to call this correctly; only the alternative-tool guidance 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?

Schema description coverage is 100%, so both parameters are already documented, establishing a baseline of 3. The description restates the category filter ('Pass `category` for one group') and only loosely paraphrases maxTokens as 'limits the length of the response', which is actually less precise than the schema's note that required workflow guidance is always returned outside the budget.

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 and resource ('Returns Better Design's review rules for UI code') and enumerates the rule groups and their severity dimension, so the agent knows exactly what payload to expect. It stops short of distinguishing itself from near-neighbours like get-team-rules or get-ui-principle, which an agent could plausibly confuse with this tool.

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 an explicit trigger condition: 'Use it when the user wants UI code reviewed.' It also adds an important qualifier that a clean self-review is not visual approval, which scopes expectations. However, it never names an alternative tool or a when-not condition, so sibling routing is left to inference.

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