lib_index

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

With no annotations, the description carries the behavioral burden. It discloses supported formats (PDF, JATS XML, text) and the non-obvious `limit` behavior, including the explicit guarantee that capped scans are reported as capped. It does not cover side effects, permissions, or repeat-run behavior, but surfaces the most important caveats.

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 purpose is front-loaded, followed by format support and the critical `limit` caveat. Every sentence earns its place; there is no filler or redundant restatement of the schema.

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?

The description covers purpose, scope, supported formats, and the most error-prone edge case around `limit`. Since an output schema exists, return-value detail need not be repeated. The main missing piece is explicit `recursive` semantics, but overall the tool is well specified.

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 compensate. It thoroughly explains `limit` (0 = uncapped; other values cap the scan and are disclosed in results) and implies `path` is a local directory. However, `recursive` behavior is left entirely to the schema, and supported formats are not tied to parameter semantics.

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 a specific verb ('Index') and resource ('a directory of papers already on disk'), and states the downstream purpose ('so lib_search can find them'). This clearly differentiates it from siblings like lib_search and lit_fetch, and is not a tautology.

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 a clear use case: index local papers so they become discoverable by lib_search. The qualifier 'already on disk' implies it is not for fetching remote papers, but it does not explicitly enumerate when-not-to-use alternatives.

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