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

No annotations, so the description carries the burden and does reasonably well: it discloses the return shape (count/cursor/timestamp, no rows), that the call is free via x402, and the recommended hourly cadence. It does not cover auth requirements or error behavior, keeping it short of a 5.

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 and efficient, but slightly redundant: 'Free:' opener, 'Free polling probe,' and 'price free via x402' all restate the zero-cost point, plus a bracketed metadata tail. Still compact and readable.

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?

No output schema exists, so the description must explain return values — and it does, listing changed_count, next_cursor, and as_of, plus the no-rows guarantee. Combined with the polling guidance, an agent has everything needed to call and use it correctly.

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% and the 'since' description already explains the cursor and bootstrap behavior. The prose adds only the linkage that the cursor flows from a previous next_cursor, which is marginal over the schema. Baseline 3 applies.

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 and scope: 'count of materially-moved markets changed since your cursor,' and explicitly distinguishes itself from the paid rows-returning delta by noting it returns 'changed_count, next_cursor, and as_of only — no rows.' An agent can separate this from probability_movers_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?

Explicitly names the condition and alternative: 'Poll hourly for $0 and call the paid delta only when changed_count > 0.' This gives both when-to-use (polling for cheap change detection) and the exact trigger for escalating to the sibling tool.

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