internet-standards-mcp

IANA registry lookup

iana_lookup

Read-onlyIdempotent

Look up IANA registry entries by exact value, name, or text, and get the entry's defining RFC section.

Instructions

Looks up an entry in an IANA registry (HTTP status codes, fields, methods; media types; URI schemes; port numbers; TLS cipher suites; link relations; DNS record types) by exact value or name, else by text. Returns the entry and its defining RFC section.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`query`	Yes
`registry`	Yes

Output Schema

TableJSON Schema

Name	Required	Description	Default
`exact`	Yes
`total`	Yes
`entries`	Yes
`registry`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 26, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already cover read-only and idempotent behavior, so the bar is lower. The description adds valuable behavioral context: matching logic ('by exact value or name, else by text') and return content (entry plus its defining RFC section). This goes beyond what annotations provide.

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, well-structured sentence that front-loads the core purpose, then lists supported registries, explains query semantics, and states the return value. Every clause earns its place with zero filler.

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?

With an output schema present and annotations covering safety, the description is largely complete for a lookup tool. Missing edge cases like 'not found' behavior and details on 'text' matching are minor gaps, not blockers. Overall it is adequately comprehensive.

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 0%, so the description must compensate. It does enumerate registries (partially redundant with the enum) and clarifies that query matches exact value/name or text. However, it does not explicitly map the two parameters or address formatting, case sensitivity, or text matching nuances. Adds some but not full meaning.

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?

The description clearly states a specific verb ('looks up'), resource ('IANA registry'), and enumerates the registry categories. It is immediately distinguishable from RFC-focused sibling tools like rfc_info and search_rfcs, so an agent can select it without deep schema inspection.

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?

The context implies usage for IANA lookups versus RFC-related siblings, but there is no explicit when-to-use or when-not-to-use guidance, nor any mention of alternatives. The usage is inferable but not directly stated.

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

Deploy Server