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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely new context: an explicit cost of $0.001 USDC per successful call via x402 on Solana, plus an HTTPS endpoint alternative. That payment/rate context is exactly the kind of behavioral detail annotations cannot express.

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?

Purpose is front-loaded in the first sentence, with examples, bounds, pricing, and endpoint following in a compact block. Six inline examples are slightly more than needed (two or three would suffice) but each earns its place by illustrating output scale.

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?

With no output schema, the description compensates by showing literal return values, so the agent knows the response is an integer count. Domain, cost, transport, and safety profile are all covered; only the sibling-relationship gap remains.

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 carry the load. It restates the 1–100000 range already in the schema, but the worked examples (1→0, 3→7, 27→111) add real semantic meaning about what the returned count represents and how large values behave.

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 a specific computation ('How many Collatz steps it takes to reach 1') and pairs it with concrete input/output examples, so an agent knows exactly what is computed. It does not, however, differentiate itself from the many near-identical siblings (collatz_length, collatz_step, collatz_glide, collatz_drop), which an agent would need to distinguish among.

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?

There is no statement of when to use this tool versus the nine other collatz_* siblings; the description only gives the domain of n. An agent must infer from the examples that this is a total-step count rather than a single step or glide record.

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