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

Despite readOnlyHint=true covering the safety profile, the description adds substantial behavioral context: the return includes 'archive grounding and change rationale', the result 'already carries the rendered palette and its PNG, PDF, ASE, JSON and CSS downloads', and — critically — a warning about a known failure mode: 'Never present the archive anchors a colour was derived from as the colours you are recommending.' The palette_finalize routing also defines follow-on behavior. This far exceeds what annotations alone provide.

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 longer than minimal (about 4 sentences) but every sentence carries operational weight: core purpose with examples, return contents, download handling instruction, a critical caution, and a workflow handoff. It is front-loaded with the core function in sentence one. Slightly denser than strictly necessary, but the extra length is justified by the failure-mode warning and sibling routing that would otherwise be absent.

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 100% schema coverage, an output schema, and readOnlyHint annotation, the description is nearly complete: it covers purpose, return contents, downloads, a key caution, and follow-on workflow. The one genuine gap is the interplay between n_results (multiple variants possible) and the instruction to 'call palette_finalize once with those exact colours' — it is ambiguous whether finalize should receive a single chosen variant or all returned variants.

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 schema fully documents all 6 parameters and the baseline is 3. The description adds marginal value by giving concrete natural-language feedback examples ('more melancholic, too corporate add warmth, or better for Gen Z luxury') that illustrate the intended tone of the feedback parameter, but it does not substantively clarify other parameters beyond what the schema already states.

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 opening sentence states a specific verb+resource+method: 'Refine an existing palette using natural language feedback.' It clearly distinguishes itself from siblings like palette_generate (creating new palettes), palette_finalize (committing a final choice), and palette_analyse (analyzing). The examples of feedback types further pin down what the tool does.

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 gives clear context for use — you call this when you have a current palette and natural language feedback to refine it. It explicitly routes to an alternative: 'If you go on to choose a final palette OF YOUR OWN from this evidence, call palette_finalize once with those exact colours.' It lacks an explicit when-not statement (e.g., 'use palette_generate for new palettes'), but the 'existing palette' constraint plus the sibling routing makes usage conditions clear.

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