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

Annotations declare readOnlyHint=true, and the description adds meaningful behavioral context beyond this: it states the tool is deterministic, not an LLM call, always instant, and never consumes archive or LLM credit. This is exactly the kind of operational transparency that helps an agent choose it confidently. It doesn't enumerate return semantics, but the output schema exists to cover that.

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 but purposefully so—every sentence carries routing-relevant information. It front-loads the core purpose and key traits (deterministic, instant, no cost) before usage examples. Slightly long but each clause earns its place; no filler words.

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 one parameter, full schema coverage, readOnlyHint annotation, and an output schema present, the description is complete. It covers what the tool does, when to use it, what inputs look like, and its operational characteristics. Nothing essential is left unexplained for an agent to invoke it 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 coverage is 100% with a single 'goal' parameter described as 'Plain-English description of what you're trying to do.' The description substantially enhances this by giving concrete example phrases ('I have a brand colour and want to check it against competitors') that illustrate the acceptable free-text format. Given only one well-covered param, this is strong added value.

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 clearly states a specific verb+resource ('deterministic tool-routing lookup') with concrete examples of input goals and its output behavior. It explicitly distinguishes its role among siblings by naming similar tools it helps disambiguate (palette_specify vs interior_specify vs house_specify).

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 explicit when-to-use guidance: 'Use this before guessing between similarly-named tools' with concrete examples. It provides example input formats and describes the routing behavior (first tool, next tool, which NOT to start with), making the usage context unmistakable.

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