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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: typography is derived from the brand's own website rather than generated, and the write is a literal passthrough of the font names supplied. It does not mention auth/permission needs, but for an idempotent, non-destructive setter this is close to sufficient.

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?

Two sentences, front-loaded with the core action and the critical constraint (write exact names, don't guess). The parenthetical is dense but informative; no sentence is filler.

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 nothing about return values needs explaining, and annotations carry the safety profile. The description covers the one thing that could go wrong with this tool — fabricating font names — and tells the agent how to source real ones, which is everything needed to invoke it correctly.

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% and each parameter is already documented (including 'from list_brands' and 'not a guess'), so the baseline is 3. The description's emphasis on exact, non-invented font names largely restates what the schema already says for headingFont and bodyFont, adding little new per-parameter meaning.

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 (sets a brand guide's heading and body font) and explicitly frames it as a direct write rather than a generation step, which cleanly separates it from regenerate_brand_guide_section and generate_brand_guide. The 'same way the dashboard's manual Typography fields do' anchor makes the operation unambiguous.

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 precondition — have the correct font name in hand first — and names concrete routes to obtain it (ask the owner, or read a fresh get_brand_guide result after retry_brand_ingest). It also states a clear prohibition: never invent a font name. That is when-to-use guidance that routes the agent across sibling tools.

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