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

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior. The description adds useful non-annotation context: paid x402/Solana access, the price per successful call, and an HTTPS endpoint. It does not explicitly state the return type, though 'whether' implies a boolean.

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?

Front-loaded with the core predicate and examples, followed by range, pricing, and endpoint details. Every sentence adds useful information for invoking or accessing the tool.

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 one-parameter predicate with no output schema, the description is nearly complete: it states semantics, range, examples, cost, and access path. The only minor gap is not explicitly saying the response is a boolean.

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?

With 0% schema description coverage, the description must carry parameter meaning. It gives the valid range for n and illustrative values, but the range duplicates schema min/max and it does not further define the vampire-number property or parameter behavior.

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 predicate: whether n is a vampire number, with concrete true/false examples and the valid range. It is clear what the tool does, but it does not differentiate itself from siblings like vampire_fangs, vampire_count, or vampire_next.

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 is implied as testing a single integer for the vampire property, and the n range is given. However, there is no explicit guidance on when to use this versus sibling tools such as vampire_fangs or vampire_low.

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