toolkit-mcp-server

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toolkit-mcp-server: encode value

toolkit_encode_value

Read-onlyIdempotent

Encode or decode text to/from base64, base64url, hex, or URL percent-encoding. Handles binary data losslessly and ignores whitespace in hex/base64 inputs.

Instructions

Encode or decode a value across base64, base64url, hex, or URL (percent) encoding, in either direction. Set operation to "encode" to transform raw UTF-8 text into the chosen encoding, or "decode" to recover the original bytes from an encoded value. Decoded bytes come back as UTF-8 text by default; set outputEncoding to "hex" or "base64" to receive them re-encoded instead, which is lossless for binary data and transcodes between encodings (a base64 digest to hex, for example). Decoding never substitutes replacement characters: bytes that are not valid UTF-8 text are reported as a recoverable error that points at outputEncoding. Whitespace in hex, base64, and base64url values is ignored, so line-wrapped MIME bodies and PEM bodies decode as-is (drop PEM's -----BEGIN/END----- lines, which are not base64). base64url uses the URL-safe alphabet (- and _ instead of + and /); url applies encodeURIComponent and percent-decoding. A value that is malformed for the chosen encoding is reported as a recoverable error, not a silent best-effort.

Input Schema

TableJSON Schema

Name	Required	Description
`value`	Yes	The value to transform — raw text for encode, an encoded string for decode. Whitespace is ignored when decoding hex, base64, or base64url; a url value is taken literally.
`encoding`	Yes	The encoding to apply: base64, URL-safe base64url, hex, or URL percent-encoding.
`operation`	Yes	"encode" transforms text into the encoding; "decode" recovers the bytes from an encoded value.
`outputEncoding`	No	Decode only: how the recovered bytes are returned. utf8 (used when omitted) returns text and fails when the bytes are not valid UTF-8; hex and base64 return the raw bytes re-encoded, losslessly. Rejected when operation is "encode".

Output Schema

TableJSON Schema

Name	Required	Description
`error`	No	Present when the call failed. Absent on success.
`result`	No	The transformed value: encoded text for encode; for decode, the recovered bytes as UTF-8 text, hex, or base64 per outputEncoding.
`encoding`	No	The encoding that was applied.
`operation`	No	The operation that was performed.
`outputEncoding`	No	How result renders the decoded bytes: utf8 text, hex, or base64. Present for operation "decode".

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedv2.3.1Sep 25, 2026

changedInput schema / properties / operation / description

Previous value: -"\"encode\" transforms text into the encoding; \"decode\" recovers text from an encoded value."New value: +"\"encode\" transforms text into the encoding; \"decode\" recovers the bytes from an encoded value."

addedInput schema / properties / outputEncoding

Added value: +{
+  "description": "Decode only: how the recovered bytes are returned. utf8 (used when omitted) returns text and fails when the bytes are not valid UTF-8; hex and base64 return the raw bytes re-encoded, losslessly. Rejected when operation is \"encode\".",
+  "enum": [
+    "utf8",
+    "hex",
+    "base64"
+  ],
+  "type": "string"
+}

changedInput schema / properties / value / description

Previous value: -"The value to transform — raw text for encode, an encoded string for decode."New value: +"The value to transform — raw text for encode, an encoded string for decode. Whitespace is ignored when decoding hex, base64, or base64url; a url value is taken literally."

changedOutput schema / properties / error / properties / data / properties / reason / description

Previous value: -"Machine-readable failure mode. Declared by this tool: `decode_failed`: operation is \"decode\" but value is malformed for the chosen encoding. Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `decode_failed`: operation is \"decode\" but value is malformed for the chosen encoding. `decode_not_utf8`: operation is \"decode\", outputEncoding is utf8 (or omitted), and the decoded bytes are not valid UTF-8 text. `output_encoding_not_applicable`: operation is \"encode\" and outputEncoding was supplied; it selects how decoded bytes are returned. Other values are possible when a failure originates below the handler."

changedOutput schema / properties / error / properties / data / properties / reason / examples

Previous value: -[
-  "decode_failed"
-]New value: +[
+  "decode_failed",
+  "decode_not_utf8",
+  "output_encoding_not_applicable"
+]

addedOutput schema / properties / outputEncoding

Added value: +{
+  "description": "How result renders the decoded bytes: utf8 text, hex, or base64. Present for operation \"decode\".",
+  "enum": [
+    "utf8",
+    "hex",
+    "base64"
+  ],
+  "type": "string"
+}

changedOutput schema / properties / result / description

Previous value: -"The transformed value (encoded text, or the decoded original)."New value: +"The transformed value: encoded text for encode; for decode, the recovered bytes as UTF-8 text, hex, or base64 per outputEncoding."

Changed6 schema fields changedv2.2.2Aug 22, 2026

changedInput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

changedOutput schema / $schema

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

addedOutput schema / anyOf

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "encoding",
+      "operation",
+      "result"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

addedOutput schema / properties / error

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `decode_failed`: operation is \"decode\" but value is malformed for the chosen encoding. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "decode_failed"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

removedOutput schema / required

Removed value: -[
-  "encoding",
-  "operation",
-  "result"
-]

Addedv2.0.0Jun 28, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The description goes far beyond the readOnlyHint/idempotentHint annotations by disclosing key behavior: decoding never substitutes replacement characters, malformed values produce recoverable errors, whitespace is ignored in certain encodings, base64url uses the URL-safe alphabet, and url uses encodeURIComponent. This is exactly the kind of behavioral context an agent needs beyond 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?

The description is longer than average but every sentence carries useful information, including edge cases, error behavior, and encoding-specific details. The first sentence front-loads the core purpose. It is dense rather than redundant, though it could be tightened slightly without losing value.

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?

Given the tool's complexity — four parameters, three enums, two operations, and multiple encoding formats — the description is remarkably complete. It covers error handling, whitespace tolerance, PEM/MIME scenarios, binary data handling, and output format options. With an output schema also present, nothing an agent needs to call and understand this tool is missing.

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

Parameters5/5

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

Even though schema coverage is 100%, the description adds substantial meaning to the parameters: it explains what "decode" returns by default, how outputEncoding enables lossless transcoding, how whitespace handling affects the value parameter, and which alphabet base64url uses. This is meaningful value beyond the schema's enumerated definitions.

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 opens with a specific verb and resource combination: "Encode or decode a value across base64, base64url, hex, or URL (percent) encoding, in either direction." This unambiguously identifies the tool's operation and scope, and clearly separates it from siblings like hash_value or generate_id, which perform different transformations.

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 provides clear operational guidance: when to use "encode" vs "decode", and when to set outputEncoding. It also gives practical use cases like decoding base64 digests and PEM bodies. However, it does not explicitly name sibling tools or state when this tool should be preferred over them, though the context is strong enough that an agent can infer appropriate usage.

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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