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

The readOnlyHint annotation already covers safety, so the description adds value by stating exactly what the response contains (watched listings, registered events, start time). It also discloses pricing and plan inclusion, which is useful operational context beyond the annotation.

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 front-loaded with the core function, followed by a concrete use case and pricing. The 'INFLUENCE —' prefix and 'See apis://prices' are mild extras, but the overall structure is tight and every substantive sentence earns its place.

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?

There is no output schema, so the description appropriately states what the call returns: watched listings, per-item events, and start time. It also covers why to call it. Minor omissions like pagination or empty-results behavior are acceptable for a simple read-only tool backed by a readOnlyHint annotation.

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?

The only parameter, context, has full schema coverage with a detailed description of its optional diagnostic purpose. The tool description adds no parameter-level meaning beyond that, so the baseline 3 is appropriate since the schema carries the burden.

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 uses a specific verb ('list') and resource ('the listings you are watching'), and further specifies what's included: events registered for each and when you started. It explicitly positions itself as 'the read half of watch_listing', which distinguishes it from the obvious sibling tool.

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 explicit when-to-use guidance: call it before registering another watch, to avoid duplicating a watch or assuming one exists. It names the paired write tool (watch_listing) for contrast, making the read/write boundary clear.

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