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

The description adds useful behavioral context beyond the annotations: it states the ordering ('oldest to newest'), the included fields, that nothing is fetched, and that free tier shows only the last 30. The annotations are all false, so the description carries the burden and does a good job of disclosing the read-only nature and the free-tier limit.

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?

Three sentences, each earning its place: what it lists, that nothing is fetched, and the free-tier limit. Front-loaded with the core purpose and no 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?

For a simple read/list tool with no output schema, the description covers the key details an agent needs: what is returned, ordering, and the free-tier cap. It doesn't mention pagination or how to specify the watch (id vs url), but the schema covers the parameters and the tool is simple enough that this is a minor gap.

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 all three parameters (id, url, limit). The description adds the 'free shows the last 30' context, which relates to limit, but doesn't add much beyond the schema. Baseline 3 is appropriate.

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 states a specific verb ('list'), a resource ('one watch's stored observations'), and a clear scope ('oldest to newest'), and it distinguishes itself from sibling tools like price_check and price_add_manual by clarifying it reads stored observations. It also mentions the output fields (price, currency, source, confidence, min/max), so an agent can tell exactly what this tool does.

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 clear context: use it to list stored observations for one watch, and it explicitly says 'Nothing is fetched,' which helps differentiate it from price_check. It doesn't explicitly name alternative tools or state when not to use it, but the context is strong enough for an agent to select it appropriately.

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