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

Annotations already establish that the tool is read-only, idempotent, and non-destructive, so the description does not need to repeat those traits. It adds meaningful behavioral context by specifying what validation covers (mode, affected-test counts, fallbacks, non-interference evidence) and what the output includes (a conservative next action). No contradiction with annotations exists.

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-loaded sentence states the core action first ('Validate and summarize a DiffCI observation report') and then enumerates the relevant dimensions in a compact list. There is no filler or redundancy, and every clause 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 tool with one required parameter, full schema coverage, and safety annotations, the description covers the main purpose, the report content of interest, and the nature of the output (summary plus conservative next action). It does not describe error conditions or detailed output structure, but those are not explicitly required given the absent output schema and the tool's relatively narrow scope.

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% with the parameter documented as 'A diffci.observation.v1 JSON report,' so the schema already identifies the type. The description adds value by listing the salient report aspects the interpretation centers on, giving an agent a better model of what the report object is expected to contain beyond the bare type label.

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 specific verbs ('Validate and summarize') tied to a clear resource ('a DiffCI observation report') and enumerates concrete report facets (selective/full mode, affected-test counts, fallbacks, non-interference evidence, conservative next action). This clearly distinguishes it from siblings like diffci_validation_plan and diffci_verify_workflow_text, which involve planning and verification rather than report interpretation.

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 the tool is used when an agent has a DiffCI observation report and needs it validated/summarized, but it gives no explicit when-to-use or when-not-to-use guidance, and it does not mention alternative sibling tools. The usage context is inferable rather than stated, so it stops short of strong guidance.

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