source_list_files

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

With no annotations, the description carries the burden. It discloses that listed files are 'recoverable from source maps' and represent the 'pre-bundling file tree', which sets expectations about scope. But it does not mention behavior when source maps are absent, ordering, or whether all recoverable files are included.

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?

Two sentences with no fluff. The first defines the operation and the second supplies the usage context. Both sentences earn their place and the key information is front-loaded.

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 simple list tool with two optional, well-documented parameters and no output schema, the description covers purpose, scope, and use-case. It could be more explicit about return format or handling of missing source maps, but nothing critical is missing.

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% and the schema descriptions for limit and filter are already clear ('Maximum paths to return', 'Only paths containing this substring'). The tool description adds no additional parameter meaning, so the baseline 3 applies.

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 opens with a specific verb and resource: 'List the original source files recoverable from the page's source maps — the pre-bundling file tree.' It clearly differentiates this from sibling tools by framing it as a discovery step before source_get_file or setting a breakpoint, so an agent knows its role 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 second sentence gives explicit guidance: 'Use it to discover real file paths before calling source_get_file or setting a breakpoint on an original file.' This states when to use the tool and positions it relative to downstream actions, though it does not name alternatives it is better than.

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