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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is covered. The description adds meaningful behavioral context: results reflect 'currently connected' modules (implying dynamic state), and it openly states limitations (search/calculators unavailable). This goes beyond what annotations provide.

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?

Two sentences total: the first delivers the core purpose, the second scopes expectations with the limitation note. No fluff, no redundant detail, and the most important information is front-loaded.

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?

For a zero-parameter, read-only capability discovery tool, this description is sufficient. It states what will be returned (modules, formats, locales, limitations) and what is explicitly not yet available. The lack of an output schema is acceptable because the description already sets expectations.

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 and the schema is an empty object. The description needs no parameter explanation, and the baseline for 0-parameter tools is 4. Nothing is left undocumented.

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 uses the specific verb 'Discover' and names the resource: connected STILL modules, supported formats, locales, and limitations. It clearly differentiates from sibling tools like still_generate_citation and still_resolve_artwork, which perform actions rather than report capabilities.

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: use this tool to learn what modules, formats, and locales are available before invoking other STILL tools. It also pre-empts misuse by stating that search and calculators are not available yet. It does not explicitly name alternatives, but the sibling tools are distinct enough that the usage context is obvious.

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