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

No annotations are provided, so the description bears the full burden. It mentions the return value includes a JSON object or null if unmappable, but does not disclose side effects, authentication needs, or error handling behavior for invalid input or network issues.

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 concise, well-structured with markdown headings and a clear list of parameters. Every sentence adds value, though the parameter descriptions could be omitted since they duplicate the schema.

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 lookup tool without output schema, the description adequately covers purpose, parameters, and return behavior including null case. It lacks error scenarios and relation to sibling tools, but is sufficient for basic usage.

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% with parameter descriptions. The tool description largely repeats those descriptions but adds the default value for contextLines and includes a Returns section not present in the schema. It adds minimal new meaning beyond 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 looks up original source code context for a specific line and column in compiled code. It identifies the exact action and resource, and implicitly distinguishes from siblings like parse_stack and unpack_sources through its unique focus on source map lookups.

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 provides no guidance on when to use this tool versus its siblings (parse_stack, unpack_sources). It doesn't mention any context or prerequisites, leaving the agent without clear decision criteria for tool selection.

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