flow_replay

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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it does so thoroughly. It reveals that replay is server-side, not in the browser session; that dependencies are resolved from live replay responses rather than the capture; that the return format is a compact per-call report; and it states safety limits (http/https only, 10s per-request timeout, 60s/200-step cap). This is unusually complete behavioral context.

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 a single dense block, but every sentence earns its place: core action, verification purpose, runtime dependency behavior, return format, and safety limits. It front-loads the main verb and resource before diving into details, and the use of a colon-separated return-format example is efficient. No fluff, no repetition.

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 the tool's complexity and the absence of an output schema, the description does an excellent job of explaining behavior, return format, and safety caps. Minor gaps remain: what happens when the 60s/200-step cap is exceeded, how sessionId selects the session, and how non-http URLs are handled (skipped vs. errored) are not stated. These are small relative to the rich context provided.

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 75%, so the schema already documents three of four parameters; the description adds extra meaning by tying sinceSeq to the flow_mark window and by explaining the 60s/200-step overall budget around timeoutMs. The sessionId parameter is not covered in either the schema or the description, which is a small gap, but the added context meaningfully enriches the parameter semantics overall.

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 opens with a specific verb ('Execute') and a clearly bounded resource ('the captured network calls'), then narrows the scope with 'since the last flow_mark (or the whole buffer)' and 'server-side (Node fetch, NOT the browser session)'. It also states the verification goal ('this verifies a synthesized flow actually reproduces'), which distinguishes it from sibling tools like net_get or flow_export.

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 gives a clear when-to-use context: you run this after synthesizing a flow to check whether it actually reproduces against the server. It also clarifies that runtime dependency resolution catches broken reversed flows, which is a strong cue for choosing this over simple listing tools. It does not explicitly name alternatives or say when not to use it, but the intended workflow is unambiguous enough.

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