Run Ex command

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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. It only states that the tool 'return[s] its captured output,' but fails to warn that Ex commands can have side effects, such as `:write` modifying files or `:bnext` changing the active buffer. This is a significant transparency gap for a command executor that can alter editor state.

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?

Two sentences, front-loaded with the core action and illustrative examples. No redundant information. Every word earns its place, making it efficiently scannable for an agent.

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?

The tool is simple with one well-documented parameter, but lacks critical behavioral context around side effects and session scope. The description explains execution and output capture but does not address that commands can permanently modify files or alter Neovim state, which is essential for safe autonomous use. This is adequate but not complete.

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?

The input schema already provides a clear description of the `command` parameter (100% coverage), establishing a baseline of 3. The tool description adds value by giving concrete examples of valid Ex commands and clarifying that the leading colon is omitted, which enriches parameter understanding beyond the schema's minimal description.

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 the tool executes an Ex command, with concrete examples like `:write`, `:bnext`, and `:vsplit foo.txt`. This specific verb+resource combination differentiates it from sibling tools such as nvim_exec_lua (Lua execution) and nvim_eval (Vimscript evaluation). The purpose is unambiguous and immediately actionable.

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 implicitly defines usage by limiting scope to Ex commands and providing representative examples. It does not explicitly mention when not to use it or recommend alternatives, but the examples and the tool name make the domain clear. This earns a 4 for clear context without explicit exclusions.

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