Arc & Ledger Tax Tools

Decode an IRS notice

decode_irs_notice

Read-only

Use this when, and only when, a user mentions receiving an IRS letter or notice and wants to know what it means, the deadline, or what to do. For a state-agency letter, use triage_tax_problem with problem=state_tax instead. Give this tool the IRS notice code (e.g. CP2000, CP14, LT11) and optionally the notice date and amount shown. Set brief:true for a shorter answer.

Input Schema

TableJSON Schema

Name	Required	Description
`brief`	No	Set true for a shorter answer: skips the generic how-to-read guidance and common-error list.
`notice_code`	Yes	The notice or letter code printed on the IRS mail, e.g. "CP2000", "CP 14", "LT11", "Letter 1058".
`amount_shown`	No	The dollar amount the notice proposes or bills, if any. Optional; used only for context, never stored.
`received_date`	No	Date on the notice (YYYY-MM-DD). Used to compute the response deadline. The IRS clock runs from the notice date printed on the letter.

Output Schema

TableJSON Schema

Name	Required	Description
`relay`	Yes	Instruction to the calling assistant: relay figures and dates verbatim (identical on every response).
`next_step`	Yes	A single review link appropriate to this server surface.
`disclaimer`	Yes	General-information disclaimer (identical on every response).
`source_url`	Yes	The arcandledger.com page that backs this answer.
`server_version`	No	Server release that produced this response (matches GET /version).

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedJul 26, 2026

changedOutput schema / properties / next_step / description

Previous value: -"A single human handoff to the firm."New value: +"A single review link appropriate to this server surface."

Changed2 schema fields changedJul 13, 2026

addedOutput schema / properties / relay

Added value: +{
+  "description": "Instruction to the calling assistant: relay figures and dates verbatim (identical on every response).",
+  "type": "string"
+}

changedOutput schema / required

Previous value: -[
-  "disclaimer",
-  "source_url",
-  "next_step"
-]New value: +[
+  "disclaimer",
+  "relay",
+  "source_url",
+  "next_step"
+]

Changed2 schema fields changedJul 12, 2026

addedInput schema / properties / brief

Added value: +{
+  "description": "Set true for a shorter answer: skips the generic how-to-read guidance and common-error list.",
+  "type": "boolean"
+}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "properties": {
+    "disclaimer": {
+      "description": "General-information disclaimer (identical on every response).",
+      "type": "string"
+    },
+    "next_step": {
+      "description": "A single human handoff to the firm.",
+      "properties": {
+        "label": {
+          "type": "string"
+        },
+        "url": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "label",
+        "url"
+      ],
+      "type": "object"
+    },
+    "server_version": {
+      "description": "Server release that produced this response (matches GET /version).",
+      "type": "string"
+    },
+    "source_url": {
+      "description": "The arcandledger.com page that backs this answer.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "disclaimer",
+    "source_url",
+    "next_step"
+  ],
+  "type": "object"
+}

First observedJul 8, 2026

TDQS

A4.7/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds value beyond that by stating the brief flag skips specific content ('generic how-to-read guidance and common-error list') and that received_date drives deadline computation. It does not contradict annotations.

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 sentences, front-loaded with the trigger condition, then the alternative tool, then the input/output hint. No filler; every sentence carries routing or invocation information.

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?

Complete for a read-only decoder with an output schema. The description covers trigger, alternative, required input, optional inputs, and a display-length flag; nothing needed for correct invocation is missing.

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 100%, so the baseline is 3. The description slightly exceeds this by giving examples of notice codes (CP2000, CP14, LT11) and clarifying the optional role of date and amount ('optionally the notice date and amount shown'), which reinforces but does not exceed what the schema already documents.

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?

States a specific verb and resource ('decode' an 'IRS notice') and enumerates the three things the user wants to know (meaning, deadline, action). It also contrasts explicitly with the sibling triage_tax_problem for state-agency letters, so an agent can route without opening either schema.

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

Usage Guidelines5/5

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

Gives an explicit trigger ('when, and only when, a user mentions receiving an IRS letter or notice') plus a named alternative with its selecting condition ('For a state-agency letter, use triage_tax_problem with problem=state_tax'). This is textbook when/when-not/alternative guidance.

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

All Arc & Ledger Tax Tools tools Inspect

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