explain_diff

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

With no annotations provided, the description carries the full burden. It explicitly states the tool is read-only and does not run new checks, which covers safety and side effects. It also references a class A security classification (per D99.V), adding context. However, it does not describe potential errors, return format details, or dependencies beyond reading a report.

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 two sentences that efficiently convey the core function and key behavioral caveats. It is front-loaded with the primary purpose and contains no redundant information.

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 no annotations, no output schema, and 0% parameter coverage in the description, the tool is incomplete for an agent to use correctly. The description covers the primary action and read-only nature but lacks parameter semantics and output expectations. For a simple read-only tool, it might suffice if parameters were self-explanatory, but they are not.

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 description provides no explanation of the parameters (report, session, threshold). Schema description coverage is 0%, and the schema itself has no descriptions. The tool requires three parameters with no guidance on their meaning or format, making correct invocation difficult.

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 ('Render') and resource ('CommonMark explanation of a check report'), clearly indicating the tool's function. It also distinguishes itself from siblings by stating it does not run new checks, differentiating it from check_repo and similar tools.

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 implies usage context by stating it reads an existing ReportFile and is read-only, which suggests it should be used after checks have been run. However, it does not explicitly name alternative tools or provide a detailed when-to-use vs. when-not-to-use, but the 'does not run new checks' caveat gives clear guidance.

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