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Agent Tool-Call Diff API
x402
Agent Tool-Call Diff API is a paid API for AI agents from x402.agentutility.ai, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-15).
Compares two sequences of agent tool calls to identify added, removed, reordered, and argument-drifted calls between a before and after replay.
Price / call$0.008
Success—
StatusUnknown
How this service works
Compare two agent run sequences and see how their tool calls differ. Send before and after arrays of tool calls (name/args or tool/arguments shape) and get back which calls were added, removed, or reordered, plus per-call argument drift with the exact changed argument paths from a deep compare. The result is exact and reproducible: the same replay comparison always returns the same diff. Built for agent regression diff work: confirming a prompt or code change didn't silently alter which tools an agent calls or what it passes them. Use it as a tool call diff API, an agent action drift checker, or a replay comparison step in CI before shipping an agent change.
Output
Returns a JSON object with: `identical` boolean, `before_count` and `after_count` integers, `added` array of new calls, `removed` array of dropped calls, `reordered` array of calls that changed position, `unchanged_count` integer, and `arg_drifted` array of calls whose arguments changed — each with the call name, before/after index positions, and a list of per-argument diffs showing the JSON path, old value, and new value.
Example use cases
CI regression check before agent deploy
“Before I ship this agent update, compare the tool calls from the old run to the new run and tell me if anything changed — any calls added, removed, reordered, or arguments that drifted from their old values.”
Prompt change impact audit
“I just rewrote my agent's system prompt — can you diff the before and after tool-call sequences so I can see if the new prompt silently changed which tools the agent calls or what arguments it passes them?”
Debug unexpected agent behavior shift
“My agent started behaving differently after a dependency update. Compare these two tool-call replay arrays and show me exactly which calls are new, which are gone, and where any argument values changed, with the specific JSON paths that drifted.”
Technical details
Endpoint
POSThttps://x402.agentutility.ai/tool-call-diffWhen to prefer
Choose this endpoint when you need an exact, reproducible, deep diff of two agent tool-call sequences — specifically when you want to catch argument-level drift (not just presence/absence of calls) across replays. It is purpose-built for agent regression workflows and CI pipelines where you need deterministic, structured output rather than a fuzzy semantic comparison. Prefer it over general-purpose JSON diff tools because it understands tool-call object shapes natively and surfaces reordering as a distinct category.
Side effects
- Missing `before` or `after` arrays returns a validation error
- Arrays exceeding 500 entries are rejected
- Malformed tool-call objects (missing name/args or equivalent shape) may cause parse errors
- Payment failure via x402 results in 402 response before processing
- Mismatched tool-call object shapes between before and after may produce unexpected diff results
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"added": [],
"removed": [],
"identical": false,
"reordered": [],
"after_count": 2,
"arg_drifted": [
{
"name": "search",
"arg_diffs": [
{
"path": "$.q",
"after": "world",
"before": "hello"
}
],
"index_after": 0,
"index_before": 0
}
],
"before_count": 2,
"unchanged_count": 1
}
}Tags
x402
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