SlingHook

Compare events

compare_events

Read-onlyIdempotent

Shows field-by-field and header differences between two captured webhooks, defaulting to the previous same-type event, to reveal what changed after a failure or payload update.

Instructions

Shows what differs between two captured webhooks, field by field (JSON paths such as data.items[0].price), plus header differences. Use it for "this one worked and that one failed, what changed?" or to spot a provider changing its payload. Leave out b to compare with the previous event of the same type on the same endpoint. Changes always read from the older event to the newer one. Key order, formatting and per-delivery headers (signatures, request ids, dates) never count.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "a": "<a>"
    },
    "name": "compare_events"
  }
}

Input Schema

Name	Required	Description
`a`	Yes	First event. Which event: its number (12 or "#12", from list_events or the dashboard), "latest", "latest <event type>" such as "latest invoice.paid", or the provider's own event id such as evt_1Qx...
`b`	No	Second event, same forms as `a`. Default: the previous event of the same type on the same endpoint
`include_headers`	No	Also compare headers

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 9, 2026

TDQS

A4.5/5.0

Behavior5/5

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false. The description adds non-obvious behavioral details: comparison direction is always older-to-newer, key order/formatting/per-delivery headers are ignored, and omitting `b` compares against the previous same-type event on the same endpoint.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded and compact: the first sentence defines the operation, later sentences cover use cases, default behavior, comparison direction, and ignored differences. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a three-parameter read-only comparison tool with rich schema descriptions and annotations, the description covers what is compared, how defaults work, comparison direction, and noise exclusions. Although no output schema exists, the field-by-field diff concept is clear enough for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, and the schema itself documents event forms for `a`, the default for `b`, and the `include_headers` boolean. The description reiterates the `b` default and header comparison but adds little new per-parameter meaning beyond the high-coverage schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb-resource pair: shows what differs between two captured webhooks, field by field using JSON paths, plus header differences. This clearly distinguishes it from siblings like get_event, list_events, and replay_event.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives concrete usage scenarios such as debugging a worked-vs-failed event or spotting provider payload changes, and explains the default comparison when `b` is omitted. It does not explicitly name alternatives or when-not-to-use cases, so it falls short of a 5.

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

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