Select and navigate to a zero-based byte range in a specified live buffer using buffer ID, offset, and length for binary inspection.
Select/navigate to a zero-based byte range in the explicitly identified live buffer.
| Name | Required | Description | Default |
|---|---|---|---|
| length | Yes | ||
| offset | Yes | ||
| buffer_id | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=false, idempotentHint=false, destructiveHint=false, so the agent knows this mutates editor state harmlessly and non-repeatably. The description adds that the target buffer must be 'live' and that offsets are zero-based byte positions, but says nothing about failure behavior for a stale buffer or what the selection actually affects.
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 scope, with no filler or restatement of the tool name. Every clause contributes semantics.
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 3-parameter mutation tool with no output schema and no annotation coverage of return or error behavior, the description is only minimally adequate. It does not explain what a completed selection produces or how failures surface, though annotations cover the safety profile.
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 carry the load, and it does partially: buffer_id identifies the live buffer, offset is a zero-based byte position, and the range has a length. It still leaves units/edge cases (zero-length selection, out-of-bounds offsets, whether length is bytes or characters) undocumented.
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 concrete verb pair (select/navigate) and the resource (a zero-based byte range), plus the scoping qualifier 'live buffer'. It is distinguishable from editor_read (reading content) and the patch tools (mutating content), though it never names a sibling to sharpen the distinction.
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?
No when-to-use or when-not-to-use guidance, and no routing to alternatives such as editor_read or editor_context. The only implied precondition is 'explicitly identified live buffer', which is a constraint on the input, not usage context.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.