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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety and network access profile. The description adds value by disclosing the output format (Launch Readiness score 0-100 and past-ready fix) and the type of findings, which is beyond the annotations. It doesn't mention potential latency or limitations, but given the strong annotation coverage, this is acceptable.

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, front-loaded with the primary function, followed by usage guidance. Every word is informative, with no filler or redundancy. The title 'Run a Vibe Check' is informal but the description itself is concise and well-structured.

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 a single parameter, full schema coverage, an available output schema, and annotations, the context is nearly complete. The description adds the output type and use cases, so the agent has all necessary information to select and invoke the tool correctly. No gaps are evident.

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 has 100% coverage for the single 'url' parameter, describing it as 'full public URL of the live app to scan'. The description reinforces this with 'live URL' but adds no additional semantic detail beyond what the schema provides. The baseline of 3 applies because the schema does the heavy lifting.

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 verb 'Scan' and the resource 'a live URL', with specific objects of the scan: leaked API keys, exposed config files, and missing security headers. It also mentions the output (score and fixes), making the tool's purpose unambiguous. While there are no sibling tools to distinguish from, the description is highly specific and action-oriented.

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 states when to use the tool: 'Use before deploying, or when checking the security of an app built with AI coding tools like Cursor, Lovable, v0 or Bolt.' This provides clear context and a concrete use case. With no sibling tools, there's no need for alternative exclusions, and the guidance is fully sufficient.

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