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

The annotations already indicate readOnly, idempotent, and non-destructive behavior. The description adds valuable behavioral context: 'line-based pagination (offset/limit)' and 'Handles both text and binary files.' It does not mention error cases or binary encoding, but the added context goes beyond 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, concise, and front-loaded with the action and use case. Every sentence adds value, with no filler or repetition of schema details.

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 has no output schema and a moderate parameter count, so the description must carry return-value context. It mentions returning file content and pagination, but lacks details about how binary content is encoded, the response structure, and error behavior when files are missing. These gaps make it incomplete for an agent invoking the tool.

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% description coverage for all five parameters, so the schema already handles parameter semantics. The description only vaguely references offset/limit pagination and doesn't add meaning beyond what the schema provides (e.g., default version behavior is only in the schema).

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 reads a specific file from an app's source snapshot, using a specific verb ('read') and resource ('file from snapshot'). This distinguishes it from sibling tools like src_glob (searching for file paths) and src_grep (searching file contents).

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 starts with 'Use this when you need to read a specific file...' which gives clear usage context. However, it does not explicitly mention alternatives like src_glob or src_grep, nor does it state when NOT to use the tool.

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