watchDiagnostics

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

The description explains that the tool is a long-poll, which implies a blocking behavior—a key trait not captured by the 'readOnlyHint' annotation. However, it does not explicitly mention that it may return immediately if no changes exist or that it blocks until a timeout. Still, it adds significant behavioral context beyond the annotation.

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 compact with two sentences, front-loading the purpose and usage. Every word contributes meaning, making it highly concise without sacrificing clarity.

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 description is adequate for a tool that returns diagnostic changes but lacks details on the return format (e.g., list of diagnostics or just a signal) and does not explicitly state that it is a blocking call, which is important given the 'long-poll' nature and the timeout parameter.

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 has 100% description coverage for all three parameters. The description does not add any parameter-specific meaning beyond what the schema already provides, so a baseline score of 3 is appropriate.

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 purpose: 'Long-poll for diagnostic changes. Use after edits to wait for LSP re-validation.' It uses a specific verb ('long-poll') and resource ('diagnostic changes'), and effectively distinguishes itself from the sibling 'getDiagnostics' which returns current diagnostics rather than polling for changes.

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 explicitly says to use it 'after edits to wait for LSP re-validation,' providing clear context for when to invoke the tool. It implies an alternative (polling) without naming it explicitly, but the guidance is strong enough for an agent to understand the intended use case.

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