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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations by naming the external data source (OSV.dev) and clarifying that it checks for known vulnerabilities, which sets expectations about external dependency and scope. It does not mention return format or rate limits, but that is not critical given the 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 two sentences with zero filler. The first sentence front-loads the core function and scope, and the second sentence provides routing to alternatives. Every word 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 read-only query tool with three well-documented parameters and safety annotations, the description is nearly complete. It covers purpose, supported ecosystems, optional version behavior, and alternatives. The only minor gap is that it does not hint at the return value shape (e.g., list of CVEs or severity), but that is not essential for correct invocation.

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%, so the input schema already documents all three parameters (package, version, ecosystem) with clear descriptions. The description adds minimal extra meaning beyond the schema, mostly restating the optional version behavior and listing ecosystem examples. Baseline 3 is appropriate because the schema carries the semantic load.

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 ('Checks'), a clear resource ('a package against OSV.dev'), and the exact scope ('known vulnerabilities') with an explicit list of supported ecosystems. It also names sibling tools (cve_lookup, supply_chain_check) to distinguish itself, so an agent can tell them apart immediately.

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 explicitly tells the agent when to use this tool versus alternatives: 'Use cve_lookup when you already have a CVE/GHSA ID, or supply_chain_check for a combined verdict.' This is direct routing guidance with no ambiguity.

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