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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, but the description adds real behavioral context beyond them: no drawing, no files created, and an explicit statement of what the tool will not evaluate (root-cause validity). That last line prevents a common misuse where an agent expects qualitative judgment.

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?

Front-loaded with the trigger and examples before the return-value list, and every sentence carries routing or scope information. The enumeration of return values is somewhat long given an output schema already exists, but it is compact and reinforces the tool's boundary rather than 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?

The tool is a pure validation pass with two parameters, an output schema, and full annotation coverage, and the description still covers when to use it, what it will not do, and how it relates to the sibling. Nothing an agent needs in order to call it correctly or interpret the result 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 coverage is 100% and the schema itself documents the 6M default and nesting limits, so the description does not need to re-explain shapes. It does add cross-tool meaning by stating it takes 'the same problem and categories as make_fishbone', letting an agent reuse a payload it built for the sibling rather than reconstructing it.

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 (review a fishbone/cause-and-effect list) plus a scope boundary: 'before drawing' and 'Takes the same problem and categories as make_fishbone.' It also explicitly separates itself from the sibling by noting it 'Draws nothing and makes no files', so an agent can choose between check_fishbone and make_fishbone without opening either 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?

Gives an explicit trigger ('when the user wants their fishbone or cause and effect list reviewed before drawing') with two concrete example utterances, and adds a negative boundary ('Does not judge whether a cause is a real root cause'). The sibling relationship is named directly, which is exactly the routing information an agent needs.

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