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

The readOnlyHint annotation covers safety, and the description adds rich behavioral detail: hay_contrast snaps input to Hay's nearest named hue rather than rotating it, returns covered:false for tertiary regions, and the result already carries rendered palettes plus PNG, PDF, ASE, JSON, and CSS downloads. It also discloses a guardrail about never presenting archive anchors as the recommended colours, which is valuable beyond the annotation.

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 the core purpose, and every major sentence adds useful information. It is on the longer side, especially the Hay contrast explanation and the customer-facing directives, but those earn their place because they prevent incorrect output presentation.

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 full input schema, output schema, and readOnlyHint annotation, the description is complete enough for an agent to invoke the tool correctly and handle its result. It covers the central output, an important edge case, download availability, and the follow-up palette_finalize behaviour, so no critical guidance 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?

Schema description coverage is 100%, so the baseline is 3. The description adds meaningful semantics by explaining the hay_contrast mode in depth, including its distinct snapping behavior and edge-case output. It does not add much specific meaning for hex, but the schema already documents the format with an example.

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: it returns complementary, triadic, analogous, and split-complementary harmonies matched to named archive colours. It then clearly separates the hay_contrast mode from the fixed-angle types, so an agent can tell what this tool uniquely does even among many colour-related siblings.

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 about what the result contains and tells the agent to show rendered palettes to the customer. It also provides a concrete downstream rule: if the agent chooses its own final palette from this evidence, it must call palette_finalize once with those exact colours. It stops short of explicitly naming alternative harmony tools or giving a precise 'use this instead of X' statement.

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