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

Annotations already declare this a read-only, idempotent, non-destructive, closed-world operation, so the safety profile is covered. The description adds genuinely new behavioral detail: matching is per-line and case-insensitive, results are grouped by module, and an empty search string returns the full list rather than nothing. It doesn't describe truncation or result volume for the empty-search case, which would be the remaining risk.

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, no filler, with the core purpose front-loaded and the parameter edge case immediately after. Every clause earns its place.

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 read-only listing tool with full annotation coverage and no output schema, the definition covers purpose, grouping, and the one parameter's edge cases. A note on result size or bare-word vs phrase matching would close the remaining gap, but nothing essential to invoking it is missing.

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?

Schema description coverage is 0%, so the description must carry the single parameter - and it does, explaining that `search` filters lines case-insensitively and that the empty string is a valid 'return everything' value. That is meaningful semantics an agent could not derive from {"type":"string"} alone. It stops short of giving match syntax or examples, so not a 5.

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 gives a concrete verb and resource: it lists AILANG builtin functions with documentation and groups them by module. That is specific enough to distinguish a builtin reference lookup from execution tools like ailang_run or ailang_eval, though it does not explicitly contrast with near-neighbours such as stdlib_search or docs_search.

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?

Usage is implied rather than stated - an agent can infer this is a reference/browse tool, and 'empty returns everything' hints at the browse-all case. There is no explicit when-to-use versus stdlib_search or docs_search, and no guidance on what to do with the results.

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