FedReg Tracker

Get codified CFR text changes

get_cfr_changes

Read-onlyIdempotent

Changes to codified CFR text from the eCFR (ecfr.gov): which sections got a new version, when (version, amendment and eCFR issue dates), whether eCFR marks it substantive or removed, links to the eCFR page and XML for that date, and Federal Register documents that probably made the change. Parts in watchlists are checked daily; any other part is read on first request. Give cfr_title and cfr_part (or a section like 63.2), or a watchlist with CFR filters. Version metadata, not a text diff; the eCFR is not the official legal edition.

Input Schema

Name	Required	Description
`limit`	No
`since`	No	Earliest version date (default 90 days ago).
`until`	No	Latest version date.
`section`	No	Section, e.g. 63.2.
`cfr_part`	No	Part, e.g. 63 or 1910.
`cfr_title`	No
`watchlist`	No	Watchlist name or id.

Schema Changelog

Changes observed during successful MCP inspections.

Changed9 schema fields changedOct 16, 2026

addedInput schema / properties / cfr_part / description
```
Added value: +"Part, e.g. 63 or 1910."
```
addedInput schema / properties / cfr_part / maxLength
```
Added value: +20
```
addedInput schema / properties / cfr_title / maximum
```
Added value: +50
```
addedInput schema / properties / cfr_title / minimum
```
Added value: +1
```

addedInput schema / properties / limit

Added value: +{
+  "maximum": 200,
+  "minimum": 1,
+  "type": "integer"
+}

addedInput schema / properties / section

Added value: +{
+  "description": "Section, e.g. 63.2.",
+  "maxLength": 30,
+  "type": "string"
+}

addedInput schema / properties / since

Added value: +{
+  "description": "Earliest version date (default 90 days ago).",
+  "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+  "type": "string"
+}

addedInput schema / properties / until

Added value: +{
+  "description": "Latest version date.",
+  "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+  "type": "string"
+}

addedInput schema / properties / watchlist

Added value: +{
+  "description": "Watchlist name or id.",
+  "maxLength": 80,
+  "type": "string"
+}

First observedOct 14, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds genuinely new behavior: watchlisted parts are refreshed daily while any other part is read on first request (a latency/caching implication), plus the authoritative-source caveat that the eCFR is not the official legal edition. That is substantive context an agent cannot get from the annotations.

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

Conciseness4/5

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

Front-loaded with the payoff (what changes and what metadata comes back), then refresh behavior, then input forms, then caveats. Dense but nearly every clause carries distinct information; the one long enumeration sentence is the only mild drag on readability.

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?

There is no output schema, so the description carries the full return-value burden and does so: it lists the fields returned, the date semantics, the links, and the related Federal Register documents. Combined with the refresh model and the official-edition disclaimer, an agent has everything needed to call and interpret this tool.

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?

Schema coverage is 71%, and the schema documents 'since' (default 90 days ago), 'until', 'section', 'cfr_part' and 'watchlist', but leaves limit and cfr_title bare. The description compensates by explaining the accepted input combinations (title+part, or section, or watchlist) and the 63.2 / 1910 / 63 examples, which is meaning beyond the field names themselves.

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?

Names a specific resource (codified CFR text changes from the eCFR) and enumerates exactly what a result contains: version/amendment/issue dates, substantive-vs-removed marking, eCFR page and XML links, and candidate Federal Register documents. The closing clause 'Version metadata, not a text diff' cleanly separates it from diff-oriented siblings like compare_regulatory_documents.

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 invocation conditions: supply cfr_title + cfr_part, or a section like 63.2, or a watchlist with CFR filters. It also signals a scope boundary ('not a text diff'). It stops short of explicitly naming the alternative tool to use for text comparison, so it is clear context rather than full when/when-not routing.

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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