Look up original source position

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does add useful context about coordinate systems (one-based line, zero-based column) and the direction of mapping. However, it does not disclose failure behavior, the shape of the returned source position, or any preconditions (e.g., mapId must already be parsed).

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 a single sentence that is front-loaded with the verb and key details. No filler or redundant information. Every word earns its place.

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 a simple lookup but has no annotations, no output schema, and a minimal description. It omits what 'original source position' actually looks like (e.g., file, line, column), error handling, and any dependency on prior sourcemap parsing. Given these gaps, the description is insufficient for an agent to use it confidently.

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 description coverage is 0%, so the description must compensate. It clarifies 'line' and 'column' by specifying that the line is one-based and the column is zero-based. However, it says nothing about 'mapId', which remains opaque. Thus it adds value for two of three parameters but not all.

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 a specific action ('Map') with a specific resource ('a one-based generated line and zero-based column back to an original source position'). It distinguishes this from sibling sourcemap tools like sourcemap_fetch_and_parse or sourcemap_parse_v4 by focusing on the lookup/mapping operation.

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 gives no guidance on when to use this tool versus the many sourcemap-related siblings (e.g., sourcemap_fetch_and_parse, sourcemap_coverage). It does not mention prerequisites, such as needing a parsed map, or contexts where another tool is preferable. No exclusions are provided.

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