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Find every direct and indirect caller affected by changing a symbol by tracing the reverse call graph across hops, so you can update all code before refactoring.

Instructions

Trace the blast radius of changing a symbol: starting from the given symbol, walk the reverse call graph — direct callers, their callers, and so on across multiple hops — and return every symbol that could be affected by a change to it. Each affected symbol comes with a depth field (how many hops away it is) and a resolution field naming which index-wide lookup resolved that call edge (e.g. same-file, scoped, global-unique — scoped/global-unique both mean a single matching definition was found index-wide, see docs/mcp-tools.md), so results are grounded in real, resolved call relationships rather than a text search for the symbol's name (which cannot follow more than one hop and cannot tell a real call from a coincidental name match). Use this tool before refactoring — e.g. changing a function's signature or behavior — to find every place in the codebase that may need to change as a result, including indirect callers that a single-hop "find references" would miss. The response can be truncated to fit within a token budget; when it is, truncated is set to true and truncated_count reports how many additional affected symbols were left out. Results come from the local corbel index built by corbel index and only reflect the repository as of the last index run.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
fileNoOptional file path to disambiguate when multiple symbols share this name.
nameYesThe symbol name to start the impact analysis from.
token_budgetNoOptional cap on the size of the response, in estimated tokens. Defaults to corbel's built-in budget if omitted.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A4.6/5.0
Behavior5/5

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

No annotations are provided, so the description carries the full behavioral burden. It discloses that results are grounded in resolved call relationships, includes depth and resolution semantics, mentions truncation via truncated/truncated_count, and states that results reflect the last corbel index run. This is rich, non-obvious behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is longer than average but every sentence adds substantive value, including use case, output field meanings, truncation behavior, and index freshness. It is front-loaded with the core purpose; minor redundancy exists around the comparison to text search, but it is not excessive.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the complexity of a multi-hop reverse-call-graph traversal, no output schema, and no annotations, the description is exceptionally complete. It explains what the tool returns, how results are resolved, when truncation occurs, and what data source backs the analysis, leaving few operational ambiguities.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline of 3 applies. The description reinforces that 'name' is the starting symbol and explains why 'file' matters for disambiguation, but it does not add new parameter-level meaning beyond the schema descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a concrete verb and resource: 'Trace the blast radius of changing a symbol' by walking the reverse call graph across multiple hops. It clearly distinguishes itself from a shallow text search and from single-hop 'find references' tools, so an agent can tell it apart from siblings like find and get_symbol.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly says 'Use this tool before refactoring' and gives concrete scenarios such as changing a function's signature or behavior. It also warns against using a text search or single-hop find references for this purpose, which provides clear when-not-to-use guidance relative to alternatives.

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

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