fetchFetch one indexed search result by stable ID, or fetch a verified publisher page via libraryId + url previously obtained from link-only query-docs. The URL must belong to the exact authorized source and version; no arbitrary web fetching.
| Name | Required | Description | Default |
|---|---|---|---|
| id | No | ||
| url | No | ||
| libraryId | No |
Changes observed during successful MCP inspections.
Input schema / properties / libraryIdAdded value: +{
+ "maxLength": 500,
+ "minLength": 3,
+ "type": "string"
+}Input schema / properties / urlAdded value: +{
+ "format": "uri",
+ "type": "string"
+}Input schema / requiredRemoved value: -[
- "id"
-]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the safety profile is covered. The description adds a genuinely useful constraint beyond annotations: the URL must belong to the exact authorized source and version, and arbitrary web fetching is disallowed. It does not cover error behavior or what happens on a mismatched URL.
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, both earning their place: the first states the two retrieval modes, the second the authorization constraint. Front-loaded with the primary action, though the first sentence is dense and packs several concepts together.
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 read-only fetch with four safety annotations and no output schema, the description covers both invocation paths and the key authorization restriction. It leaves gaps on what content is returned, pagination, and behavior when the ID or URL does not resolve.
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 load, and it does map parameters to meaning: 'id' identifies an indexed search result, while 'libraryId' + 'url' together identify a verified publisher page. It still does not clarify optionality/mutual exclusivity of the three params or why no parameters are required.
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 states a specific verb (fetch) and resource (one indexed search result, or a verified publisher page) and names the two distinct retrieval modes. It contrasts with the multi-result siblings by emphasizing 'one indexed search result', though it never explicitly distinguishes itself from 'search' or 'list-library-versions'.
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?
It states the precondition for the URL mode ('previously obtained from link-only query-docs') and an explicit negative boundary ('no arbitrary web fetching'), which tells the agent when this tool is not appropriate. It stops short of naming a fallback sibling for cases outside these two modes.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.