Encode text into RFC 3986-compliant URL format for safe use in URLs and query strings, or decode percent-encoded strings back to readable text.
URL-encode or decode a string. RFC 3986 compliant encoding for URLs and query strings.
| Name | Required | Description | Default |
|---|---|---|---|
| input | Yes | Text to encode or URL-encoded 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 declare readOnlyHint=true, and the description is consistent, adding the RFC 3986 compliance detail and the scope for URLs and query strings. This provides useful context beyond the annotations, though it doesn't discuss edge cases or error behavior, which is acceptable for a pure utility.
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?
A single, well-structured sentence with zero filler. The purpose is front-loaded, and the RFC compliance detail adds value without bloat.
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, read-only utility, the description covers purpose and compliance sufficiently. No output schema is present, but the tool's output (encoded/decoded string) is self-evident, so nothing critical is missing.
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 clear descriptions for both `input` and `action`. The description adds no parameter-specific detail beyond what the schema already provides, so the baseline 3 is appropriate.
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 states a specific verb (encode/decode), the resource (URL strings), and notes RFC 3986 compliance, clearly distinguishing it from sibling tools like base64_encode_decode and decode_jwt. An agent immediately understands the tool's scope.
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 URL encoding/decoding but does not explicitly contrast with alternative encoding tools (e.g., base64_encode_decode, decode_jwt). No when-not-to-use guidance is provided, leaving selection to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.