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

Annotations already establish readOnly/idempotent/closed-world, and the description adds real value on top: the billing model (one credit per map point), the grid bounds, and an explicit non-execution guarantee. It omits what happens with insufficient balance or whether the profile must exist, which are the remaining behavioral unknowns.

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?

Two sentences with no waste; the cost-and-balance payload is front-loaded and the non-execution caveat follows immediately.

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?

There is no output schema, and the description does name the two things returned (credit cost and workspace balance), which is sufficient for a read-only preview. The gap is profile_id semantics and error/insufficient-credit behavior.

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 0%, so the description carries the full burden of explaining all three parameters. It usefully converts grid_rows/grid_cols into a cost formula ('one per map point') and bounds, but profile_id — a required UUID that determines which workspace is billed — is never explained.

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 (Show) and resource (Rank Tracker scan cost plus workspace balance), and scopes it to a 3x3–12x12 grid. The final sentence 'Does not run anything' cleanly separates it from the request_rank_scan sibling without needing the schema.

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?

The 'Does not run anything' clause implies a preview-before-request use case, which is clear guidance for an agent. It stops short of naming request_rank_scan as the follow-up action or stating when this preview should be skipped, so it lacks explicit alternatives.

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