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

With no annotations, the description carries the full behavioral burden and does so richly: 404/no charge on no change, cursor always returned, $0.02 per call, payment source, failed/empty free, and a clear non-advice disclaimer.

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?

The purpose is front-loaded and the paragraph is dense but mostly earns its place with output, billing, and safety details. It could be split for scanability, but there is little pure filler.

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?

Given no annotations and no output schema, the description compensates by listing the return fields, error semantics, cost model, and usage context. An agent has enough information to invoke it correctly and interpret empty results.

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 description coverage is 100%, so the schema already documents q, ids, cursor, and min_move. The description adds only the 'up to 20 market ids' limit and otherwise repeats what the schema provides, making 3 the appropriate baseline.

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 and resource: 'Prediction market watch/monitor' with the exact scope 'only what changed since your last check.' It clearly distinguishes itself from search or odds siblings by returning deltas, moved flags, newly-listed markets, and a cursor.

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?

Explains when to use it: after a previous check, to monitor changes via up to 20 ids or a topic. It does not explicitly compare against every sibling (e.g., pm_odds, pm_gaps), but the context is clear enough for an agent to select it.

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