Feature List

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

Annotations already mark the tool read-only (readOnlyHint=true) and not open-world, so the description's burden is lighter. It adds valuable behavioral detail by specifying the exact return shape {schema, count, templates} and per-template fields {doc, refs, required, optional, emits}, which goes beyond the annotations. It does not mention pagination or ordering, but that is a minor gap for a read-only listing tool.

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 main action is front-loaded ('List every registered FEATURE TEMPLATE'), followed by compact domain context, return shape, and usage guidance. The PowerCopy/UDF analogy and issue reference add mild noise, but every remaining clause contributes useful information.

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 parameters and no output schema, the description skillfully supplies the missing return-value contract and sibling relationship, making the tool usable in isolation. It could still mention ordering or scale expectations for a large list, but overall the description is complete enough for correct invocation and interpretation.

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?

The tool has zero parameters, so the baseline is 4 and there is nothing in the schema to document. The description compensates by explaining the structure of returned templates, making the tool's behavior meaningful despite the empty input schema.

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: 'List every registered FEATURE TEMPLATE', and then clarifies the domain concept with concrete inputs (frame, f_/e_ tag, axis) and scalar parameters. It also distinguishes itself from siblings feature_schema and feature_instantiate by positioning itself as the 'directory to browse before picking one.'

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 explicitly gives the usage context: it is the directory to browse before choosing a template via feature_schema/feature_instantiate. This names the relevant alternatives and the order in which they should be used, leaving no ambiguity about when to call feature_list.

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