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

Goes well beyond the annotations by disclosing that stored indexed text is returned when available, otherwise extraction happens on the fly without persisting, and that unsupported types (PDF, PowerPoint, images) return empty text with an explanatory note. These are non-obvious behaviors an agent needs to interpret results correctly.

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?

Front-loads the core action, then layers in caching behavior, the unsupported-type edge case, and the alternative in three dense sentences with no filler. Every sentence 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 one-parameter read tool with no output schema, the description surfaces the caching semantics, the empty-text failure mode for unsupported types, and the escalation path. Nothing an agent needs to call it and interpret its result 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 100% and the schema already documents code_or_id as a REF code or UUID. The description restates the same accepted forms with an example, adding only marginal value over the structured field, so the baseline of 3 is appropriate.

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?

States a specific verb and resource ('Return the extracted plain text of a Reference Library item') and names the identifier form. It implicitly distinguishes itself from library_index, library_search, and library_upload, so an agent can route correctly without opening the schema.

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?

Clearly scopes when this tool applies (reading extracted text by REF code/id) and points to traceable_library_index when the goal is persisting text for search. It doesn't explicitly contrast with traceable_library_search, but the when/when-else context is clear.

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