Replace a line range

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

Beyond the annotations (destructiveHint=true, readOnlyHint=false), the description discloses two meaningful behaviors: the buffer is saved by default (triggering format-on-save) and fresh LSP diagnostics are returned. This adds concrete side-effect and output context not present in the structured fields.

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?

The description is three short, focused sentences: the core operation, the default save behavior with consequence, and the return value. Every sentence adds distinct information with no redundancy or fluff.

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?

Given the tool's moderate complexity, full schema coverage, and destructive annotations, the description covers the essential context: line-range inclusivity, default save, side effect on format-on-save, and the return of LSP diagnostics. With no output schema, stating that the result is diagnostics is sufficient for an agent to anticipate the response.

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%, with each parameter already described (e.g., 'inclusive', '1-based'). The description repeats this information (e.g., '1-based, inclusive') and adds no new param semantics beyond the schema, so it meets the baseline but does not exceed it.

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?

The description starts with a specific verb and resource: 'Replace lines start_line..end_line (1-based, inclusive) with new text.' This clearly distinguishes it from sibling tools like nvim_insert_lines and nvim_edit_text by defining the exact operation and scope (line range).

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 description provides clear context: it replaces a line range and saves the buffer by default, which alerts the agent to format-on-save side effects. However, it does not explicitly name alternative tools or state 'when not to use,' though the line-range scope gives some implied differentiation from insert/edit operations.

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