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

The description discloses cost (3 credits, charged only when saved), time (~1 minute), and the post-save review requirement ('needs the user's review'). It also warns about retries. These details go well beyond the sparse annotations (readOnlyHint=false) and give the agent a realistic expectation of side effects and resource usage.

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?

The description is a single dense paragraph but every sentence earns its place: action, cost, timing, usage guidance, retry warning, and return values. It's front-loaded with the primary purpose. It could be split into bullet points for readability, but it's far from verbose.

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 one-parameter tool with no output schema, the description covers all essential aspects: what it does, prerequisites, side effects (cost/time), and what it returns (brand_kit_id, open_url, source_url). Nothing an agent needs to decide whether to call 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?

The schema already describes website_url ('The website address, like acme.com.'), achieving 100% coverage. The description doesn't add further parameter-level detail, but it correctly references the parameter in context. Per the rubric, with full schema coverage the baseline of 3 applies, and there's no extra value to raise 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?

The description opens with a specific verb+resource pair: 'Read a public website and save its brand...' and lists the exact brand components (colors, fonts, radius, logo). It clearly distinguishes itself from sibling tools like create_brand_kit (manual creation) and list_brand_kits (retrieval) by framing this as an extraction-from-URL operation.

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 explicitly instructs to 'Call list_brand_kits first and reuse a matching website's kit unless the user explicitly wants another extraction' — a concrete precondition and alternative path. It also forbids retrying ('Do not call this again to retry'), which prevents an agent from looping on a failed extraction. This is exemplary usage guidance.

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