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

With no annotations, the description carries the full burden. It usefully discloses the re-execution scope ('without re-running the whole run') and enumerates the verdict categories, which is real behavioral context. However, it omits mutation/reversibility, permissions, and any precondition that a recorded run's spans must be supplied.

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 dense sentence that front-loads the action, the scope, and the output, with zero filler. Nothing could be trimmed without losing 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?

For a tool with nested object inputs, a confusing 0 required parameters, no annotations, and no output schema, the description covers purpose and the verdict output well. It still leaves preconditions (which inputs are actually required, whether any state is mutated) unaddressed.

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 67%: 'span' and 'spans' are documented in-schema, while 'span_id' is not. The description reinforces single-span selection ('ONE recorded span', 'span_id selects the one to fork') but adds no format, default, or required/optional clarification, so it only marginally exceeds the schema.

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?

States a specific verb+resource (fork-replay ONE recorded span) and the resulting artifact (an attribution verdict), with a precise scope qualifier ('from a failed agent run', 'without re-running the whole run'). It is clear what the tool does, though there are no siblings to differentiate against.

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 debugging context ('from a failed agent run', 'ONE recorded span') but never states explicit when-to-use vs when-not or prerequisites, e.g. that the run must already be recorded. Usage is inferable rather than prescribed.

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