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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it does so thoroughly. It discloses the cost per call, the fact that no API key or account is needed, the 402 response for missing payment, the inclusion of a baseline and 7 days of polling, and the need to persist watch_id and key for later polling. This is far beyond the average tool description and gives the agent a realistic picture of side effects and prerequisites.

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 description is long but every sentence carries distinct, high-value information: core behavior, persistence model, type requirements, payment model, and free alternatives. The most important usage constraint is front-loaded, and the payment/error behavior is placed precisely where it matters. No filler is present.

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 the tool's complexity, 16 parameters, no output schema, and a large sibling set, this description is remarkably complete. It covers what the watch does, how to pay, what happens without payment, how to poll results, which parameters are required per type, and where to go for a free alternative. The only minor missing detail is a fuller return-format description, but the instruction to persist watch_id and key provides enough guidance.

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 69%, and the description adds critical conditional logic that the schema alone lacks: 'url/rss/x402 need url; price needs coin plus a threshold; edgar needs ticker or cik.' This meaningfully helps an agent form valid inputs. It does not enumerate every parameter, but the schema already documents most of them with examples, so the description compensates well for the main ambiguity.

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?

The description opens with a specific, concrete statement: 'Keep watching a source between agent runs and alert when it changes.' This names a clear verb, resource, and standing behavior that distinguishes create_watch from the check_* siblings, which are one-off checks. It also positions itself relative to poll_alerts and the free trial endpoints.

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?

The description gives strong guidance on when to use this tool: for persistent watching between runs, with type-specific requirements spelled out. It also names a free alternative for demos and 24-hour trials, which helps an agent decide not to call create_watch when a wallet-free option is acceptable. It stops short of explicitly enumerating when-not cases, such as 'use check_* for a one-time immediate check,' so it misses full 5-level explicitness.

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