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

Beyond the readOnlyHint and destructiveHint annotations, the description adds important behavioral semantics: is_available does not guarantee quota or every tool/media combination, missing capability flags mean unsupported on this discovery surface, default_models_web_search is search-only, Auto accounts for attachment capabilities, and no LLM call is made. These caveats materially affect how an agent interprets results and costs.

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 enumeration, then use cases, then disambiguation caveats. It is longer than many tool descriptions, but each sentence adds distinct value; only the trailing doc-link and model-selection aside are auxiliary, keeping it appropriately sized rather than padded.

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 discovery tool, the description covers purpose, when to call, interpretation pitfalls, auto behavior, behavior (no LLM call), and a documentation pointer. With an output schema present, an agent has everything it needs to decide whether and how to invoke the tool.

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 accepts no parameters, so the schema has nothing to document; the description's field-level detail relates to output semantics rather than inputs. Per the 0-parameter baseline, no additional parameter meaning is required.

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 starts with a specific verb and resource — 'List available model keys, nominal capabilities, languages, strategies, auto-selected defaults and organization profile_limits' — making the tool's scope unmistakable. The detailed enumeration also distinguishes it from sibling list_* tools such as list_schemas and list_records without needing to name them.

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 explicitly states when to use the tool ('when choosing explicit models or checking plan limits') and when not to ('ordinary calls may omit models or use auto without fetching this large catalogue'). This gives an agent a clear decision rule for invoking it.

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