get_diagnostics

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

No annotations are provided, so the description carries the full burden. It discloses two key behaviors: returning diagnostics for all open files when file_path is omitted, and requiring files to be opened first. However, it doesn't mention side effects (likely none), return format, or failure modes, which would improve transparency.

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 sentences long, with every sentence adding value: purpose, usage, and behavioral notes. It is front-loaded with the verb and resource, making it easy to scan.

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 simplicity (1 optional param, no output schema), the description covers purpose, usage, default behavior, and a prerequisite. It lacks explicit mention of the return structure, but for a diagnostics tool this is relatively clear from the context and typically sufficient.

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 schema already fully documents the single parameter (file_path) with its optionality and default behavior, giving 100% coverage. The description repeats this information without adding extra semantic detail, so it meets the baseline for covered parameters.

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: 'Get diagnostic messages (errors, warnings) for files.' It uses a specific verb ('get') and resource ('diagnostic messages') and differentiates from sibling tools like get_completions and get_code_actions by focusing on error identification.

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 tells the agent when to use it ('Use this tool to identify problems in code files') and provides important usage details: optional file_path behavior and the prerequisite that files must be opened first. It does not explicitly name alternatives or exclusions, but the context is clear.

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