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

With no annotations, the description carries the full burden. It discloses one behavioral trait: 'Does not move money'. However, it fails to mention other important behaviors such as whether it creates a persistent resource, requires authentication, is idempotent, or what side effects occur. This is inadequate for a mutation tool.

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 a single, efficient sentence that front-loads the core purpose and key differentiators. There is no fluff or redundancy, making it highly concise.

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 (8 parameters, no output schema, no annotations), the description is severely incomplete. It mentions a webhook contract but does not describe it, and it does not explain how parameters like tier, cohorts, signals, or min_confidence should be used. An agent would struggle to call this tool correctly with only the provided information.

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 only 25% (2 out of 8 parameters have descriptions). The description adds no parameter-level detail, only vaguely referencing 'filters given' without mapping to specific parameters. It fails to compensate for the low schema coverage, leaving most parameters unexplained.

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 clearly states it is the exact subscribe call for a watch (mode=watch), includes filters, tier, price, metering, and webhook contract, and explicitly notes it does not move money. This distinguishes it from sibling tools like buy_product and quote_watch, providing a specific verb and resource.

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?

It provides context that this is a subscription call and mentions 'mode=watch' and 'Does not move money', which implies it is for actually subscribing rather than quoting or purchasing. However, it does not explicitly mention when to use it over alternatives like quote_watch, nor does it state any exclusions or conditions.

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