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

The description adds value beyond annotations by disclosing the settlement fee ($0.001 USDC), no charge on failure, and the JWT decode caveat (no verification). While annotations already indicate readOnly=false, these extra details provide practical context for an agent's decision-making. It does not contradict annotations and offers useful operational behavior.

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 three sentences total, each with a distinct purpose: listing operations, stating when to use, and stating cost/failure policy. It is tightly written with no filler, and the core purpose is front-loaded. Every sentence 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?

Given the presence of an output schema and the tool's compute nature, the description is complete. It covers allowed operations, exclusions, usage, cost, and failure behavior. An agent has all necessary information to invoke the tool correctly without missing critical 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?

Schema description coverage is 100% but the operation parameter's schema description is merely 'Operation to perform,' which is unhelpful. The tool description compensates by listing every possible operation value, providing essential semantics for the operation parameter. It also clarifies the purpose of input as 'Data to encode/decode,' matching the schema description but reinforcing it.

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 is an encoding/decoding utility and explicitly lists all supported operations (base64, hex, URL, JWT decode, JSON stringify/parse). It distinguishes from sibling compute tools by explicitly mentioning it is NOT for cryptographic operations and directing to compute/hash, so an agent can immediately identify when this tool applies.

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?

Usage guidance is explicit: 'MUST be invoked when an agent needs format conversion' provides a clear trigger condition, and 'Do NOT use for cryptographic operations (use compute/hash)' gives an explicit exclusion with an alternative. This fully informs when to choose this tool over siblings.

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