base64_decode

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

With no annotations, the description takes full responsibility for disclosing behavior. It reveals that both Base64 variants are accepted, missing padding is auto-fixed, and the output is either text (when valid UTF-8) or hex. This covers the key behavioral traits, though it does not mention error handling for malformed input.

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 concise sentences. The first states the operation, and the second covers input acceptance and return behavior. Every word adds value, with no redundancy or filler.

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 single-parameter utility with no output schema, the description fully specifies the input requirements and output format. It provides enough detail for an agent to select and invoke the tool correctly without further context.

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?

The schema has only a required string parameter 'encoded' with no description, making schema coverage 0%. The tool description compensates by explaining that this string is the Base64-encoded text and details accepted variants and padding behavior, adding significant semantic meaning beyond the type definition.

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 specifies the action 'Base64-decode' on 'a string', clearly stating the tool's function. It also mentions acceptance of standard and URL-safe Base64, which helps distinguish it from sibling tools like base64_encode or url_decode.

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 provides clear context on acceptable input variants ('standard and URL-safe') and auto-fix of padding, which guides when to use the tool. It does not explicitly name alternatives or exclusions, but the purpose is clear enough that usage is obvious.

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