list_lexicons

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

No annotations are provided, so the description must carry the full burden. It discloses the filtering behavior with examples and the 'Leave empty to list all' behavior, but does not mention pagination, rate limits, or whether the operation is guaranteed read-only (though 'List' implies it). It adds some context beyond the schema, but could be more explicit about response size or limitations.

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 concise and well-structured: a one-sentence purpose, a usage note, and a compact Args block with examples. It front-loads the main action and avoids unnecessary detail. Every sentence contributes value.

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 simple list tool with one optional parameter and an output schema, the description is complete enough. It explains what it does, when to use it, and the parameter semantics. It does not describe return values, but the output schema covers that. It lacks caveats like pagination or auth, but given the tool's simplicity and the presence of an output schema, the description suffices.

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 schema provides only a 'namespace' string with default '', with no description. The description's Args section fully explains the parameter: it is an optional namespace prefix, provides concrete examples ('app.bsky.feed', 'com.atproto.repo', etc.), and clarifies that leaving it empty lists all. This adds significant meaning beyond the schema, compensating for the 0% schema description coverage.

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 'List all AT Protocol lexicons, optionally filtered by namespace prefix,' which clearly identifies the verb (list), resource (AT Protocol lexicons), and scope (optional namespace filter). It also distinguishes itself from the sibling tool get_lexicon by stating this is for discovering lexicons before fetching specific ones. This gives a precise purpose.

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 states 'Use this to discover available lexicons and their NSIDs before fetching specific ones with get_lexicon,' providing a clear when-to-use context and referencing the next step. It does not mention alternatives like search_lexicons or exclusion cases, but the guidance is sufficient for typical use.

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