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

Beyond the readOnlyHint annotation, the description discloses privacy-relevant behavior ('The image is never stored — processed in memory only'), the fact that the result carries pre-rendered downloads (PNG, PDF, ASE, JSON, CSS), and a crucial representational constraint ('Never present the archive anchors...'). This significantly exceeds the annotation's coverage.

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 dense and front-loaded with purpose, but it contains several distinct clauses (method, outputs, use cases, privacy, warnings, next-step) that make it longer than ideal. Every sentence earns its place, so it earns above-average marks, though it is not as crisp as a two-sentence definition.

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?

Given the output schema and annotations, the description is complete for invocation: it covers required input, number of colours, output contents, download artifacts, privacy, use contexts, and the follow-up tool call if needed. Nothing essential is missing for an agent to call image_palette 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%, so the baseline is 3. The description reinforces that images are base64 encoded and that up to 5 colours are returned, which mirrors schema fields, but it does not add materially new parameter-level semantics beyond what the schema already documents.

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 and resource ('Upload an image... extract its dominant colour palette') and immediately distinguishes the tool by the archive-matching with cultural provenance, K-means++ extraction, and the named outputs (RAL, WCAG, downloads). This makes it clear what image_palette does and how it differs from extraction-only siblings like extract_image_colours or palette_extract.

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 gives explicit target use cases ('Works for product photography, interior photos, artwork, brand assets, and mood boards') and an explicit alternative/next step: if the agent chooses its own final palette, call palette_finalize. It does not state exclusions or when not to use the tool, so it falls short of a 5.

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