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

Beyond the readOnly/idempotent annotations, the description discloses output ordering, the exact contents of each capsule, the verification methodology (two witnesses on two hosts), and the empty-list-with-note behavior. This is substantial behavioral context that annotations alone would not convey.

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, front-loaded with the core result and then adding provenance and edge-case behavior. The middle sentence is long but each clause earns its place; the flourish 'freshness a base model cannot have' is the only somewhat dispensable phrase.

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 read-only listing tool with no output schema, the description gives enough shape of the returned capsules, sorting, filter options, and empty-case behavior for an agent to call it correctly. Remaining details like accepted slug lists and date format are covered by the schema, so nothing critical is missing.

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 100%, so the baseline of 3 applies; both since and section are already fully documented with formats, defaults, and examples. The description adds only the generic 'optionally filter ... on/after a date or within one section' and no extra meaning beyond the schema.

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 opening phrase names the resource precisely: recent dated price-change capsules ordered newest-first, and the second sentence defines a capsule as a vendor price movement with before→after, date, and sources. It is clearly distinct from search/compare/products tools, though it does not explicitly name the sibling it is not.

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 clearly establishes the use case: query recent dated price movements, optionally narrowed by a since date or section, and it notes the empty-list behavior when nothing qualifies. It does not explicitly contrast with siblings like price_movers or get_price_history, 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.