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

With no annotations, the description carries the full behavioral burden and mostly does: it discloses cost (free via x402), the return shape (changed_count, next_cursor, as_of only — no rows), and the cursor-chaining behavior. It does not state explicit rate limits or confirm read-only semantics beyond the hourly-poll guidance, so it falls just short of full coverage.

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-loads the 'Free:' qualifier and the core behavior, then layers the routing rule and metadata. Sentences are dense but each earns its place; the bracketed HTTP/x402/docs tail is mildly noisy but useful reference info.

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 and no annotations, the description does the heavy lifting by naming the three returned fields and clarifying that no rows come back, plus cost and polling cadence. Only auth/permission specifics and rate limits are unaddressed, which are minor for a free read probe.

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 50%: 'since' is fully documented in the schema as an opaque cursor from next_cursor, and the description only echoes the cursor concept ('changed since your cursor') without adding syntax. The enum-only 'category' param is self-evident but gets no explanation in either place, so the description does not materially compensate for the coverage gap.

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+resource+scope: 'count of materially-moved markets in the segment changed since your cursor.' It explicitly contrasts with the paid sibling ('call the paid delta only when changed_count > 0'), so an agent can separate probability_board_changes from probability_board_delta without opening either 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?

Gives explicit operating instructions: 'Poll hourly for $0 and call the paid delta only when changed_count > 0.' This names both the cadence and the alternative (delta) plus the condition that selects it, leaving nothing to inference.

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