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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering safety. The description adds valuable behavioral context beyond annotations: the hard 8-second timeout with possible partial results, the 1-hour cache, and the verified source (deps.dev). These details help the agent anticipate edge cases and reliability. No contradiction with annotations.

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 description is informative but a bit long. It front-loads the purpose and key behavior, then covers parameters, usage, source, cache, and feedback. Each sentence serves a purpose, but the parameter repetition from the schema adds slight redundancy. Overall, it is well-structured and not excessively verbose.

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 is complete for a read-only dependency tree tool. It covers the tool's purpose, behavior (timeout, cache, source), parameters (even if redundant), usage guidance, and even a fallback feedback mechanism if the result is inadequate. The presence of an output schema also covers return values. Nothing essential is missing for an agent to use the tool correctly.

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?

The input schema already has 100% coverage with descriptions for all three required parameters (package, version, ecosystem), including examples and the ecosystem list. The description essentially repeats this information without adding new semantics. It mentions 'Exact version string e.g. 1.2.3' but the schema already has a similar example. Baseline 3 is appropriate since the schema carries the parameter documentation.

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 clearly states the tool's purpose: 'Fetch the full dependency tree for a package version including transitive dependencies.' It uses a specific verb (fetch) and resource (dependency tree), and explicitly distinguishes it from the sibling security_fetch_package_vulnerabilities, making the purpose unambiguous.

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 provides explicit usage guidance: 'Use this to understand full supply chain exposure. Use security_fetch_package_vulnerabilities instead when you only need CVEs for a single package.' This clearly defines when to use this tool versus an alternative, and also mentions the timeout behavior for large trees.

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