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

Beyond the readOnly/idempotent annotations, it discloses the validation rules (unknown ids, parent cycles, >2 biological parents, impossible years) and that errors name the problem, hard limits (150 people, 12 generations, 100 emotional relationships), the drawing rule that emotional lines only appear between adjacent same-row people, the resulting "Relationships not drawn" table, and that large-chart download links expire after about an hour.

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?

Usage guidance and examples are front-loaded, and every sentence carries operational information. The single dense paragraph with long parenthetical enumerations makes it harder to scan than it needs to be, and the return-value sentence partly duplicates the output schema.

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 tool with five parameters, nested relation objects, and hard caps, the description covers inputs, refusals, limits, rendering caveats and output artifacts. An output schema exists, yet the description's brief return summary costs little and leaves nothing an agent needs unresolved.

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 already 100%, so the baseline is 3; the description adds value by enumerating the full vocabulary for relations and kinds and by stating "no label or notes" on people, which is not visible in the schema (additionalProperties is open). It stops short of explaining interaction between fields such as household membership or start/end year semantics.

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 trigger condition ("when the user wants a genogram or family diagram with standard symbols") plus two concrete example requests, and immediately states what the tool produces. An agent can tell this renders a chart rather than merely validating one, which is the plausible confusion with the sibling check_genogram.

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 gives explicit when-to-use phrasing and example utterances, and adds a real exclusion ("Relationships only: does not take health or medical details"). It does not name the sibling check_genogram or state when to prefer it, so the alternative-selection guidance is incomplete.

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