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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds genuinely new behavioral facts: returns counts only, no fact values, the $0.01 toll quote, no x402 challenge, and the HTTP equivalent endpoint. Missing only things like rate limits or exact return shape, but the added context is substantive.

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 purpose and return contents, and each clause earns its place, but 'FREE' plus '— no payment required... this tool is free' is redundant restatement of the same fact, costing a little tightness.

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 9-parameter tool with no output schema, the description covers what is returned but leaves the central required enum parameter and seven other inputs undocumented, so an agent cannot confidently construct a call from the definition plus schema alone.

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 only 22% (only name and entity_id are described), yet the description never explains the required 'stream' parameter or its four enum values, nor limit/cursor/team/league/position/series_id. With such low structured coverage the description was expected to compensate and does not.

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?

Opens with a specific verb+resource ('FREE preflight for fact_bank_status') and immediately differentiates itself from the sibling paid tool by enumerating what it returns (existence, coverage counts, history depth, freshness, servable/reason_class, toll quote). An agent can distinguish it from fact_bank_status or fact_bank_tendency_preflight without opening 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?

Explicitly states the selection condition versus the sibling: 'no payment required: call directly without payment (no x402 challenge; this tool is free)', so an agent knows to pick this when it wants the data without paying. It doesn't spell out an ordered workflow (e.g., call this before fact_bank_status), so it falls just short of a 5.

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