addy-mcp

list_failed_deliveries

Read-only

Retrieve emails that addy.io failed to deliver or quarantined, with paging and filters by inbound, outbound, or quarantined type to troubleshoot missed messages.

Instructions

List emails that addy.io failed to deliver (or quarantined).

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "list_failed_deliveries"
  }
}

Input Schema

Name	Required	Description
`page`	No	Page number (1-based)
`page_size`	No	Results per page (1-100)
`email_type`	No	Filter by type; 'inbound_quarantined' shows mail quarantined by rules or spam checks

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.2Nov 12, 2026

TDQS

A3.5/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds the useful behavioral detail that quarantined mail is included in results, but says nothing about default ordering, default page size, or what a result record contains.

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?

A single front-loaded sentence with no filler; the parenthetical adds scope information rather than redundancy. Nothing could be removed without losing meaning.

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

Completeness3/5

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

For a read-only, three-parameter list tool with full schema coverage, the description covers what the tool returns at a high level. However, with no output schema present, it leaves the return shape (fields per failed delivery, ordering, pagination defaults) entirely undocumented.

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%, including a clear explanation of the email_type enum, so the schema carries the parameter semantics. The description's '(or quarantined)' mildly reinforces the inbound_quarantined filter but adds no new syntax or format guidance.

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

Purpose4/5

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

The description gives a specific verb (List) and resource (emails that addy.io failed to deliver), and adds the scope nuance that quarantined mail is included. It does not explicitly name how it differs from siblings like get_failed_delivery or download_failed_delivery, though the plural 'List' implies a collection versus a single record.

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

Usage Guidelines3/5

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

Usage is only implied by the purpose: an agent should call it when it wants an overview of failed/quarantined mail. There is no explicit when-to-use, no mention of alternatives (get_failed_delivery, resend_failed_delivery, delete_failed_deliveries), and no note on prerequisites or pagination strategy.

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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