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

Annotations already declare read-only, idempotent, and non-destructive behavior. The description adds valuable behavioral context about determinism (byte-identical results) and what mismatch fields indicate (data, rules, platform version, or trace), which goes beyond the minimal safety hints and helps the agent anticipate outcomes.

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, front-loaded with the core purpose, followed by behavioral detail and a clear use case. Every sentence earns its place with no fluff or repetition of schema fields.

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 moderately complex with nested objects and no output schema. The description explains what the tool does, what it proves, and how to interpret mismatches, but it does not describe the exact return format. Given the absence of an output schema, a bit more return detail would be helpful, but the description remains largely complete for decision-making.

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 parameters themselves are already documented. The description adds high-level meaning by tying contracts to 'same input + same rules' and mentioning possible mismatch causes, but it does not enrich individual parameter semantics beyond what the schema provides. Baseline 3 is appropriate.

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 starts with a specific verb 'Verify' and names the resource 'two replay contracts' with a clear outcome: 'same input + same rules = same result, byte-identical.' It also distinguishes itself from siblings by focusing on deterministic execution equivalence and mismatch localization, making its purpose unambiguous.

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 provides explicit use cases: 'prove a past decision reproduces today or that a migration changed nothing.' It does not explicitly state when not to use it or name alternative tools, but the context is clear enough to guide appropriate selection among the sibling tools.

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