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

No annotations are provided, so the description carries the behavioral disclosure burden. It adds meaningful context beyond the schema: the tool depends on an already-running language server, is non-build invariant, and returns diagnostics in milliseconds. This implies a read-only, non-destructive operation, which is sufficient for this tool type.

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 with zero filler. The first sentence front-loads the purpose and key differentiators (fast, no build, language server), and the second adds a concrete usage trigger. 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?

For a simple diagnostics tool with no output schema and no annotations, the description covers what it returns (errors/warnings), when to use it (after editing), and its precondition (already-running language server). The only minor omission is explicit behavior if the server is not running, but that is not critical for invoking it correctly.

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 description coverage is 100%, so the baseline is 3. The description adds no additional meaning for file, limit, or severity beyond what the schema already documents; it does not compensate for any gaps because there are none.

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 names a specific verb and resource ('compiler diagnostics for one file') and distinguishes the tool from the symbol-focused sibling tools (find_symbol, find_references, etc.). The phrase 'errors and warnings in milliseconds, without a build' precisely scopes what the tool does.

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 explicit workflow guidance: 'Run this after editing to confirm the change compiles.' It does not name alternatives or exclusions, but the sibling set is all symbol-navigation tools, so there is no realistic alternative to confuse it with. The 'without a build' and 'already-running language server' context clarifies when it is appropriate.

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