Copies specified source lines byte-exact into a destination pane, inserting after a target line or appending them.
Byte-exact copy of source lines into a destination pane (after a target line, or append).
| Name | Required | Description | Default |
|---|---|---|---|
| toPane | No | Default fromPane | |
| endLine | No | Last line to copy (inclusive). Default startLine | |
| fromPane | No | ||
| afterLine | No | Insert after this line. Omit to append | |
| startLine | Yes | First line to copy (1-indexed) |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does disclose one meaningful trait: the copy is byte-exact, i.e. non-transforming, and it mutates the destination pane. It omits failure behavior (out-of-range lines, missing destination pane), and it does not clarify the model/output pane model even though that is central to how the copy behaves.
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 operation and scope, and the placement nuance is parenthetical rather than buried in a second paragraph. No filler; it could be slightly tighter by mapping directly to the pane parameters.
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 five-parameter mutating tool with no annotations and no output schema, the description is thin: it never explains what 'model' vs 'output' panes mean, what line indexing (1-indexed) implies, or what the call returns. An agent must reconstruct the pane concept entirely from the enum values.
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 80%, so the schema already documents startLine, endLine, afterLine, and the pane enums, which puts the baseline at 3. The description adds the conceptual notion of a destination pane and the append-vs-insert choice, but fromPane has no schema description and toPane's 'Default fromPane' text is ambiguous, and the description does not resolve that.
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 (copy) and resource (source lines) with the destination and an explicit qualifier 'byte-exact', which distinguishes it from transforming siblings like perch_edit, perch_patch, or perch_write. It stops short of naming a sibling alternative directly, so it lands just below the top band.
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 parenthetical clarifies placement mechanics ('after a target line, or append') but says nothing about when to choose this over perch_edit, perch_patch, or perch_write, nor any prerequisite such as needing a valid destination pane sourced from perch_read. No when/when-not guidance is present.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.