MailFixture

webhook_deliveries

Recent delivery attempts for one webhook endpoint (status, attempts, last error) — the first place to look when events aren't arriving.

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": {
      "webhook_id": "<webhook_id>"
    },
    "name": "webhook_deliveries"
  }
}

Input Schema

Name	Required	Description	Default
`limit`	No	Max deliveries to return (1..=200, default 50).
`webhook_id`	Yes	Webhook endpoint id (uuid).

Schema Changelog

Changes observed during successful MCP inspections.

First observedJul 11, 2026

TDQS

A4.2/5.0

Behavior4/5

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

No annotations provided, so description carries full burden. It discloses the read-only nature (querying delivery history) and returned fields, but does not specify recency limits or pagination. Adequate but could be more detailed.

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?

Single sentence, front-loaded with purpose and key details. No wasted words.

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

Completeness4/5

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

No output schema, so description should detail return value structure. It mentions fields but lacks specifics on whether it returns a list or single item, and pagination. Nevertheless, sufficient for a simple diagnostic tool.

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 covers 100% of parameters with descriptions. Description adds minimal value beyond implying webhook_id is the endpoint identifier. Baseline 3 is appropriate.

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?

Description clearly states it returns recent delivery attempts for one webhook endpoint, listing fields (status, attempts, last error) and providing a usage context ('first place to look when events aren't arriving'), distinguishing it from diagnostic siblings like test_webhook.

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?

Explicitly suggests using this tool for troubleshooting failed deliveries, but does not mention when not to use it or alternative tools like test_webhook for testing. Good context but lacks exclusions.

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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