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

With no annotations, the description must carry the behavioral burden. It usefully discloses that the operation is deterministic, requires no network, and costs $0.003 via x402, but says nothing about error behavior on invalid decode input, output format, or the 400,000-character input ceiling.

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?

Two compact sentences, front-loaded with the core capability and followed by supporting facts about determinism and pricing. The telegraphic 'Deterministic, no network. Price $0.003 via x402.' fragments are dense but each earns its place.

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 4-parameter tool with no annotations, no output schema, and zero schema description coverage, the description covers codec semantics but omits return-value shape (especially for decode), failure modes, and size limits, leaving meaningful gaps.

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 0%, so the description must compensate. It does explain the codec choices in detail (base58 Bitcoin alphabet, URI percent-encoding) and clarifies that url_safe means standard vs URL-safe, but it never explains the required `mode` parameter as a field nor the role and limits of `text`.

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?

States a specific verb pair (encode/decode) and resource (UTF-8 text) and enumerates the exact codec family supported, which cleanly separates it from siblings like sha256 or uuid_mint that also transform text.

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 explains what can be encoded but gives no when-to-use guidance, no conditions for choosing between this and sibling text-transform tools, and no exclusions. The 'default' note on base64 is a schema default, not usage guidance.

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