Describe a design tool

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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuine value beyond that by disclosing the content of the response — modes with option semantics, website settings with ranges and recommended values, credit rule, required inputs and result kind — which matters because there is no output schema.

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 first sentence is a long run-on list, and 'its settings' is listed twice ('what its settings do to the result' and 'its settings (the website controls with ranges...)'), which reads as redundant rather than clarifying. The trigger sentence is crisp and well placed at the end, but the enumeration could be tightened.

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 no output schema, the description carries the burden of describing the return content and does so thoroughly: modes, option meanings, settings with ranges and recommended values, credit rule, required inputs, result kind. It is complete enough to know what an agent will get back, with only minor overlap/redundancy.

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?

There is a single `tool` parameter with 100% schema description coverage (including the td_... vs bare-id convention), so the schema does the heavy lifting. The description adds no extra meaning about the parameter itself, which is the baseline 3 when coverage is full.

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 enumerates exactly what the tool returns about another tool (best use, comparisons, settings, modes, credit rule, inputs, result kind), so the resource is unambiguous. However, it is written as a noun-phrase list rather than a verb+resource statement, and it never distinguishes itself from siblings like `guide` or `list_tools`, which plausibly overlap.

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 two concrete triggers: call before running a tool whose modes the user has not chosen, and call when the user asks what a mode does. That is actionable context, but there are no when-not conditions and no routing to the sibling `guide`/`list_tools` alternatives.

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