Extract the exact implementation of a class, method, or function by symbol name to avoid reading an entire source file.
Extract the exact implementation of a single class or function by symbol name (e.g., 'PaymentGateway' or 'PaymentGateway.charge' or 'charge'), avoiding the need to read the entire file.
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | Path to the source file. | |
| symbol | Yes | Name of the class, method, or function to extract. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the full behavioral burden, and it discloses little. It says nothing about read-only nature, what happens when the symbol is missing or ambiguous (e.g. multiple 'charge' methods across classes), whether surrounding context or imports are included, or whether the output is raw source text.
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?
One sentence, front-loaded with the action and resource, with the examples and the rationale ('avoiding the need to read the entire file') doing useful work. Nothing is redundant.
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 two-parameter read tool with full schema coverage and no output schema, the description covers the core mechanics adequately. It leaves unresolved the failure and ambiguity cases an agent would want to know before calling, which is a meaningful gap even at this complexity level.
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 the baseline is 3, but the description genuinely adds meaning by demonstrating the accepted symbol syntax including qualified 'Class.method' form, which the schema's 'Name of the class, method, or function' does not convey. This is real value beyond the structured field.
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?
States a specific verb and resource — 'Extract the exact implementation of a single class or function by symbol name' — and gives concrete symbol forms ('PaymentGateway', 'PaymentGateway.charge', 'charge'). It does not name or contrast with the sibling code_skeleton, which likely overlaps in purpose, so it stops short of a 5.
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?
Usage is implied by the phrase 'avoiding the need to read the entire file', which signals the token-saving context and that you should already know the symbol name. There is no explicit when-not guidance and no alternative tool is named, so an agent must infer the boundary with code_skeleton.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.