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

With no annotations, the description carries the transparency burden. It clearly discloses the key behavioral trait: this operation does not apply the patch, making it non-mutating. It stops short of detailing return values or error behavior, but the core side-effect-safe nature is explicit.

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?

A single, front-focused sentence that states the purpose and primary constraint ('without actually applying it'). There is no wasted text or redundancy.

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, but without an output schema the description should clarify return semantics. 'Check whether' implies a boolean result, and the non-mutating nature is stated. Missing details like how malformed patches are handled, but for a validation tool this is adequate.

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% (both parameters described in the schema), so the description adds no new parameter semantics beyond the existing field descriptions. The baseline of 3 applies because the schema fully documents the 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 uses a specific verb ('check') and identifies the resource ('unified diff patch' and 'original text') with a clear scope: validate applicability without applying. This distinguishes it from siblings like apply_patch and diff_stats by emphasizing the non-mutating validation intent.

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 phrase 'without actually applying it' implies a safe validation use case, contrasting with apply_patch. However, it does not explicitly name alternatives or provide exclusions, leaving the when-not-to-use scenario implicit.

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