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Definition and Bound Span

definitionAndBoundSpan

Read-only

Find the definition of a symbol at a cursor position and also get its text span to know exactly which characters form the symbol.

Instructions

Like 'definition', but also returns the span of the symbol at the cursor. Useful for understanding exactly which characters constitute the symbol being queried. Returns both the definition locations and the textSpan of the queried symbol.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "file": "<file>",
      "line": "<line>",
      "offset": "<offset>"
    },
    "name": "definitionAndBoundSpan"
  }
}

Input Schema

Name	Required	Description
`file`	Yes	File path (absolute or relative to cwd)
`line`	Yes	1-based line number
`offset`	Yes	1-based column offset

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.1.1Jul 12, 2026

TDQS

A4/5.0

Behavior3/5

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

Annotations already indicate readOnlyHint=true, so the tool is read-only. The description adds that it returns definition locations and the textSpan, which is useful but not extensive. No contradictions exist between description and annotations.

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

Conciseness5/5

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

The description is very concise with three short sentences. It front-loads the key comparison to 'definition', then adds usage context, and finally states the return values—all without unnecessary words.

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

Completeness4/5

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

The description adequately explains the tool's purpose and its difference from 'definition'. However, since there is no output schema, more details about the exact structure of the returned textSpan would improve completeness.

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 coverage is 100% for all 3 required parameters, so baseline is 3. The description does not provide any additional information about the parameters beyond what the schema already documents.

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 clearly states 'Like 'definition', but also returns the span of the symbol at the cursor.' It names the specific verb 'returns' and resource (definition locations and textSpan), distinguishing it from the sibling 'definition' tool.

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

Usage Guidelines4/5

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

The description explicitly references the sibling 'definition' and explains the added value ('also returns the span'), implying when to use it. It also states 'Useful for understanding exactly which characters constitute the symbol,' providing clear context. However, it does not explicitly state when not to use it or mention alternatives beyond 'definition'.

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