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

Annotations already declare readOnlyHint=true and idempotentHint=true, covering safety and retry behavior. The description adds meaningful context by specifying that it returns file paths but no content, and positions the tool for project structure exploration. This adds value beyond annotations without contradiction.

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 usage guidance, and contains no fluff. Every sentence conveys essential information: when to use it, what it returns, and what it explicitly does not return.

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 tool is simple with no output schema, but the description adequately explains the return value (file paths) and the absence of content. It also places the tool in the context of exploring project structure, making it complete for an agent to understand and invoke 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?

Schema coverage is 100%, so all six parameters have descriptions included in the schema. The tool description does not add parameter-specific details beyond mentioning glob patterns and paths, which are already covered. Baseline of 3 is appropriate given the schema's completeness.

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: discovering files in an app's source snapshot and returning file paths matching a glob pattern. The explicit 'no content' distinguishes it from sibling tools like src_read and src_grep, making the purpose unmistakable.

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 opens with 'Use this when you need to discover files,' providing direct guidance for when to select this tool. The phrase 'before reading or searching files' implies a workflow context and differentiates it from content-reading/searching siblings, though it does not explicitly name alternative tools.

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