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

Annotations already flag this as a non-readonly, non-idempotent, closed-world mutation; the description adds substantial context beyond that: no payment is performed, the caller must transfer USDC before pay_by, and rate/per-IP limits apply. It does not explicitly warn that repeated calls create additional unpaid orders (relevant given idempotentHint=false), which is the one behavioral gap.

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 action and the return payload, then moves through the payment caveat, limits, terms, and coordinates in a logical order. Dense but nearly every clause carries operational information; the parenthetical field list is slightly heavy but useful given there is no output schema.

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 mutating, non-idempotent creation tool with no output schema, the description compensates well by enumerating the returned payment fields and spelling out limits and coordinate rules. The only shortfall is the network enum ('solana' vs 'base') being described only as 'the USDC network you will pay on', while the return payload mentions a Solana reference specifically.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning: coordinate orientation (x left-to-right, y top-to-bottom, both 0..999), the cell index formula y*1000+x, and the semantic of accepted_terms as acceptance of the linked terms. It does not explain the solana vs base network choice or the 'base' payment reference.

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 and resource ('Create an order for cells') and immediately scopes the outcome ('return the USDC payment details'), listing the exact returned fields. This clearly separates it from siblings like get_order_status and check_cells_available, which do not create anything.

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?

Explicitly tells the caller what this tool does NOT do ('This tool does not pay: the caller sends the USDC transfer itself before pay_by'), which is the critical usage decision for this workflow. It also states constraints (minimum cells, max 16 colours, no image orders, rate limits, unpaid orders per IP) and the terms requirement, though it never names a sibling as an alternative for related operations.

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