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), yet the description still adds substantive behavior: silent defaulting to the 6M set when categories are omitted, hard refusal of oversized text with the offending item named, inline layout warnings, and ~1 hour expiry on large-diagram download links. Those are exactly the operational facts an agent cannot get from the structured fields.

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?

It is a dense single block, but it is front-loaded with the use case and examples, then limits, then return shape, so an agent can stop reading early and still call it correctly. A few clauses (the enumerated return artifacts) could be tightened since an output schema already exists.

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?

For a single required parameter plus two optional ones, the definition covers activation, defaults, limits, refusal behavior, link expiry and output shape. With an output schema present, it arguably over-delivers on return values rather than under-delivering, so nothing an agent needs 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%, so all three parameters are already documented, making 3 the baseline. The description does add some meaning the schema lacks, chiefly the defaulting behavior for an omitted categories array and the stated 2-to-8 / 10-cause / 5-sub-cause limits, but it does not explain page_size tradeoffs or the mismatch between the 4000-character schema cap and the 120-character guidance.

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 names a specific verb and artifact ('make a fishbone, Ishikawa or cause and effect diagram drawn for a problem') and grounds it with two concrete user-phrase examples. It also carves out scope ('Does not find, rank or verify root causes'), but it never names the sibling check_fishbone, so the agent must infer the boundary between generating a diagram and checking one.

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 opening 'Use this when the user wants...' plus verbatim example requests ('make a fishbone for late deliveries') gives clear activation conditions, and the negative scope line tells the agent this is not a root-cause analysis tool. It stops short of an explicit when-not-to-use rule or a named alternative, which keeps it out of 5 territory.

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