Get diagnostics

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

With no annotations, the description carries the full burden. It discloses the key behavioral trait of optionally scoping to a buffer, and the read-only nature implied by 'Return'. It could be more explicit about lack of side effects or output structure, but for a simple getter it is reasonably transparent.

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, no fluff. The first sentence states the core function and scope, the second provides a practical use case. Every word earns its place.

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 low complexity (1 optional parameter, no output schema, no nested objects), the description is sufficiently complete. It covers purpose, parameter behavior, and a use case, so an agent can confidently 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?

Schema coverage is 100% (the bufnr parameter is described), so baseline is 3. The description adds meaning by explaining that omitting the parameter returns diagnostics for all buffers, which reinforces and clarifies the schema's statement. This extra context elevates it above baseline.

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's function: returning LSP/diagnostic entries for a buffer or all buffers. It uses a specific verb ('Return') and resource ('LSP/diagnostic entries'), and the mention of buffer scoping distinguishes it from sibling LSP tools like nvim_lsp_hover or nvim_lsp_definition.

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 offers a clear use case ('letting the agent see and fix problems the way Cursor does'), which implies when to use the tool. However, it does not explicitly compare with alternative tools or state when not to use it, so it falls short of a full 5.

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