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

With no annotations, the description carries the full burden and does so well: keyset delta semantics, cursor stability across restarts, bootstrap behavior, the returned fields (changed_count, new next_cursor), and the $0.01 x402 price are all disclosed. Nothing material about behavior is hidden.

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 delta purpose and the cursor mechanics, and every sentence is useful. Slight redundancy: 'delta of /v1/movers' is restated immediately as 'Keyset delta of /v1/movers', costing a little space.

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, and the description compensates by naming the return fields (changed_count, next_cursor). For a single-param delta tool, nothing an agent needs in order to call and chain it correctly is missing.

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 single 'since' parameter is already documented as an opaque cursor that can be omitted to bootstrap. The description restates that flow ('pass since=<next_cursor from your last call>') rather than adding format or edge-case detail beyond the schema, so 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: it returns only 'materially-moved markets changed since your cursor' as a delta of /v1/movers. It explicitly names the sibling it complements (/v1/movers/changes for free counts), so an agent can distinguish it from probability_movers and probability_movers_changes without opening a 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 when-to-use mechanics: pass since=<next_cursor from your last call>, omit once to bootstrap, and poll the free sibling first to avoid paying when nothing changed. Both the invocation condition and the cost-avoiding alternative are spelled out.

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