Insert lines

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

The description adds behavioral context beyond annotations, notably that the tool saves by default and explains how out-of-range line numbers trigger append behavior. This is useful because annotations only provide readOnly/idempotent/destructive hints, not save or line handling semantics.

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 two concise sentences, with the primary action front-loaded. Every phrase adds value: the insertion semantics, append behavior, and save default. No unnecessary words or repetition.

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 simple insertion tool, the description covers the key behavioral aspects: insertion point, append, and save behavior. It does not mention error handling or requirements like an open buffer, but given the straightforward nature and minimal annotations, it is sufficiently complete for an agent to select and invoke the tool.

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?

While the schema already covers all parameters with 100% description coverage, the tool description adds extra meaning for the 'line' parameter by clarifying 1-based indexing and append behavior, and it restates the 'save' default. This supplements the schema without redundancy.

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 clearly states a specific action ('Insert text before the given line, 1-based') with a resource (lines in a file) and explicitly notes append behavior. It distinguishes from sibling edit tools by focusing on insertion rather than editing or other operations.

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 gives usage tips like 'Use a line beyond the end to append' and 'Saves by default,' which imply how to use parameters, but it does not explicitly state when to use this tool over alternatives like nvim_edit_lines or nvim_edit_text. No exclusions or alternative recommendations are provided.

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