list_emojis

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

With no annotations, the description carries the burden of behavioral disclosure. It does add a useful behavioral trait: the cost of $0.001 USDC via x402, which informs the agent this is a paid operation. However, it omits other relevant behaviors such as output format, read-only status, or any potential rate limits.

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 that are front-loaded with the core purpose ('list emojis') and an additional cost note. Every word earns its place, with no fluff or repetition.

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 tool, the description is minimal but incomplete. There is no output schema, no annotation coverage, and the parameter semantics are opaque. The cost disclosure adds a little context, but the lack of return type or behavior details means the agent cannot fully anticipate the tool's response.

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 input schema has a single generic 'params' object described only as 'Tool parameters as JSON object', which provides no meaningful semantics. The description adds nothing about what parameters this tool accepts (e.g., category, limit, format), leaving the agent completely in the dark about possible options.

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 'list emojis' which is a specific verb+resource, clearly indicating the tool lists emoji characters. It distinguishes from sibling list tools like list_countries and list_currencies by the unique resource. However, it lacks details on scope (e.g., all Unicode emojis, filtered categories) which prevents a top score.

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?

No guidance is provided on when to use this tool versus alternatives. The description only mentions the cost, but does not state criteria for selection, exclusions, or any specific use cases beyond the literal function.

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