US federal rules taking effect

List rules amending a CFR part

list_rules_amending_cfr_part

Read-only

Is anything changing in the part of the CFR I am subject to? Give a CFR title and part — "49 CFR 192", "40 CFR 52", "21 CFR 1308" — and get the already-published final rules that amend it, soonest effective date first, with each rule's DATES paragraph and a verbatim quote. The part is matched whole, so "40 CFR 5" never returns rules about 40 CFR 52.

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": {
      "cfr_part": "<cfr_part>"
    },
    "name": "list_rules_amending_cfr_part"
  }
}

Input Schema

Name	Required	Description
`from`	No	Optional ISO date; only rules taking effect on or after it.
`limit`	No	How many to return, 1–20. Default 20.
`cfr_part`	Yes	The CFR title and part together, e.g. "49 CFR 192". A bare part number is refused: it is ambiguous across the fifty CFR titles.

Output Schema

Name	Required	Description	Default
`rules`	Yes
`cfr_part`	Yes
`coverage`	Yes
`register`	No
`rules_matched`	Yes
`rules_returned`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedSep 21, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The readOnlyHint and destructiveHint already signal a safe read, and the description adds meaningful behavioral detail: it returns only published final rules, sorts by soonest effective date, includes a verbatim quote, and matches the part whole so "40 CFR 5" never pulls in 40 CFR 52-related rules. This goes beyond what annotations alone 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?

Three tight sentences move from user intent to input format to output behavior and edge-case matching. No filler or repetition of schema details; every sentence 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 read-only listing tool with an output schema, the description covers what an agent needs to invoke it correctly: how to ask the question, what input is required, what ordering and content to expect, and how matching is scoped. No significant gap remains.

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

Parameters4/5

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

The schema already documents all three parameters at 100% coverage, and the description reinforces cfr_part with examples, the refusal rule for bare numbers, and the exact-match semantics. It adds context beyond the schema without needing to restate from/limit.

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 names a specific action and resource: get already-published final rules that amend a given CFR part. It also states the output ordering, the DATES paragraph, and the whole-part matching behavior, making the tool's scope unmistakable even before considering siblings.

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?

The description gives concrete input examples ("49 CFR 192"), states the sort order, and warns that bare part numbers are refused. It does not explicitly contrast with list_rules_taking_effect or other siblings, but the amendment-focused wording makes the intended use clear.

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

All US federal rules taking effect tools Inspect

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