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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds real behavioral context beyond that: resolution is allowlist-limited ('Only documents Vooks publishes for agents resolve'), which explains failure modes for off-list URIs. It stops short of saying what an error or miss looks like, keeping it below a 5.

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 short sentences, front-loaded with the core action and scope, then the constraint, then the selection criterion. No redundant restatement of the title or 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?

With an output schema present, the description needn't describe return values, and it covers the remaining essentials for a single-parameter read tool: provenance of the URI, allowlist restriction, and when to prefer it over search_docs.

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 coverage is 100%, so the baseline is 3, but the description adds provenance the schema only hints at: the URI must come from search_docs and must be one Vooks publishes. That is meaningful constraint information beyond the schema's format example.

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 ('Fetch one published Vooks document whole') plus scope ('by the URI search_docs returned'), which cleanly separates it from list_docs and search_docs. An agent can tell from the first clause that this is a whole-document retrieval, not a 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?

Explicitly says when to use it ('when you need the complete text rather than an excerpt') and implicitly routes excerpt/ discovery needs to search_docs, which supplies the URI. It also states a hard when-not: 'it cannot be pointed at an arbitrary URL', so the agent knows not to pass external links.

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