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

Annotations declare readOnlyHint=false and openWorldHint=true; the description usefully explains the underlying behavior — text extraction runs locally for docx/spreadsheets/CSV/markup while webpage items are fetched (supporting the openWorld hint) — and discloses the persisted side effect. It also enumerates outcome states (character count, unsupported, noContent), which goes well beyond the annotations, though it omits auth/permission or size-limit context.

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?

Three sentences, front-loaded with the purpose, then supported types, then return states in a predictable order; no filler. It is dense and slightly long for a one-parameter tool, but every clause carries information, so it is close to optimal.

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?

With no output schema, the description correctly compensates by describing the return values (character count, unsupported=true, noContent=true plus note), and it covers the single parameter and the idempotent/persistent nature of the operation. Missing only edge detail such as re-indexing behavior or extraction limits.

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?

There is a single required parameter and schema coverage is 100%, so the schema already documents the REF code versus UUID forms. The description only restates 'identified by its REF code or id' and adds no format, validation, or fallback guidance beyond the schema — the baseline 3 for a fully-covered single param.

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+resource ('Extract and persist the plain text of a Reference Library item') with a named input key, and explicitly differentiates the outcome from siblings by naming traceable_library_search as the beneficiary. An agent can distinguish this from traceable_library_read or traceable_library_upload without opening a 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?

The description gives a clear motivating context ('so it becomes searchable ... and cheap to read') and names the downstream sibling tool, which tells the agent when this step is worth invoking. It stops short of explicit when-not-to-use guidance or prerequisites (e.g., whether the reference must be added first), so it does not reach a 5.

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