Convert text to Base64 or decode Base64 strings back to readable text, with support for standard and URL-safe formats.
Encode or decode a Base64 string. Supports standard and URL-safe Base64.
| Name | Required | Description | Default |
|---|---|---|---|
| input | Yes | Text to encode or Base64 string to decode | |
| action | Yes | "encode" or "decode" |
Changes observed during successful MCP inspections.
v1.4.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds useful behavioral context by noting both standard and URL-safe Base64 are supported, but it does not address edge cases such as invalid input handling or output details.
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 two short sentences with no filler. The core operation is front-loaded first, and the supporting detail about URL-safe Base64 follows naturally, making efficient use of every word.
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 two-parameter tool with complete schema coverage and read-only annotations, the description is largely sufficient. The only minor gap is that it does not explicitly state the return value format, but the output is strongly implied by the encode/decode operation.
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 coverage is 100%, so parameters are already well-documented. The description still adds value beyond the schema by explaining that both standard and URL-safe Base64 variants are accepted, which clarifies the allowed input format beyond the bare parameter names.
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 uses a specific verb-resource pair ('Encode or decode a Base64 string') and adds a distinguishing detail ('Supports standard and URL-safe Base64') that separates it from sibling tools like encode_decode_url. The scope is immediately clear.
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 when to use the tool (whenever Base64 encoding/decoding is needed) and the URL-safe variant support gives additional context. However, it does not explicitly mention alternatives or state when not to use this tool versus alternatives like encode_decode_url.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.