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

With readOnlyHint already declared, the description adds meaningful analytical context: it uses CIEDE2000 distance, archive context, a 0-100 distinctiveness score, and a four-level ownership verdict. It does not mention the optional competitor_provenance nuance, but the schema already covers that detail.

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 efficiently structured: a purpose question, an input list, an output list, when to use it, and what it replaces. Every sentence earns its place and there is no redundant or marketing 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?

The description, combined with the rich input schema descriptions and output schema, gives an agent everything needed to invoke this tool correctly. It covers purpose, inputs, outputs, and usage timing, while the optional competitor_provenance behavior is handled by the schema.

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%, so the baseline is 3. The description lists the main inputs (brand hex, brand name, competitor hexes and names, market, region) but does not add semantics beyond what the schema already provides. It omits the optional competitor_provenance array, but the schema explains it thoroughly.

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 clear question, 'Can this brand own this colour against these competitors in this market?', then lists the exact outputs: CIEDE2000 distances, distinctiveness score, ownership verdict, plain-English summary, and recommendation. It is specific about the resource (brand colour) and the comparison context (competitors, market, region).

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 description explicitly says 'Use before committing to a brand colour in a competitive market' and notes it 'Replaces manual colour distance checks and competitor palette analysis.' This gives clear when-to-use guidance, though it does not explicitly mention sibling alternatives or when not to use it.

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