base64_decodeDecode Base64 / Base64URL / Base32 / Hex back to UTF-8 text (keyless, offline). Set variant (default base64).
| Name | Required | Description | Default |
|---|---|---|---|
| data | Yes | Encoded data to decode. | |
| variant | No | Encoding: base64 (default), base64url, base32, or hex. |
Changes observed during successful MCP inspections.
Input schema / examplesAdded value: +[
+ {
+ "data": "SGVsbG8sIFdvcmxkIQ=="
+ },
+ {
+ "data": "U2Vuc2l0aXZlIGluZm9ybWF0aW9u",
+ "variant": "base64url"
+ }
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, establishing safe operation. The description adds context of 'keyless, offline', which reveals no external dependencies and local execution. This extra information enhances transparency beyond the annotations, though no mention of error handling or output format is included.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single sentence that efficiently communicates the core action and key constraints. It is appropriately front-loaded and contains no extraneous words, earning its place with every part contributing to clarity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple decoding tool with no output schema, the description adequately specifies the input encodings and default variant. It mentions the output format (UTF-8 text) implicitly. However, it does not address behavior for invalid input or error cases, leaving minor gaps in completeness.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, with both 'data' and 'variant' documented in the schema. The description mentions setting variant and the default base64, but the schema already lists the default. Thus, the description does not add significant meaning beyond the schema, meeting the baseline for full coverage.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool decodes multiple encodings (Base64, Base64URL, Base32, Hex) to UTF-8 text, with explicit mention of being keyless and offline. The verb 'Decode' and resource enumeration provide specificity, and the tool distinguishes from its sibling base64_encode via opposite functionality.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies usage for decoding encoded strings but offers no explicit guidance on when to use this tool versus alternatives. It does not specify when not to use it or mention any prerequisites. The context of sibling tools includes base64_encode, but the description itself lacks comparative guidance.
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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