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

Annotations already declare readOnlyHint=true, and the description reinforces this with 'Free and read-only' — mild redundancy, not contradiction. The real added value is the disclosure of what the call returns (styles, bundles, licence types with dimensions and price tiers), which the agent cannot learn from any output schema since none exists. It stops short of stating rate limits, error behavior, or pagination, keeping it below a 5.

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?

One dense paragraph, front-loaded with the usage condition before the argument and return contract. The long enumeration of returned fields is justified because there is no output schema, though a list-like layout would scan faster than the comma-chained clause.

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?

With no output schema, the description fully compensates by enumerating the return payload down to key names (font_id, bundle_id, use, dimension keys) and connecting them to the follow-up tools. Nothing an agent needs in order to call this correctly and chain it 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 single parameter's description already says 'A family id, or the id of any font in the family.' The prose restates this almost verbatim, adding no format, resolution-order, or error semantics beyond the schema. Baseline 3 is appropriate when the schema carries the load.

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 (get a font family) and immediately scopes it against the sibling search_fonts, which only finds individual fonts. The clause 'returns the family name, foundry, every style with its font_id, base price and variable flag' plus bundle and licence-type details makes the tool's role unmistakable.

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 explicit when-to-use conditions: after search_fonts when the user wants more than one style, or to inspect a foundry's licensing. It also names the downstream tools (quote_license, buy_license) and which returned keys to feed them, so the agent knows both when to call it and what to do next.

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