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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), yet the description adds real value beyond them: it discloses the two-witness/two-host verification rule and the constraint that an archive-only second witness requires the page to be the vendor's own. It also states the empty-list-with-note behavior, though it is silent on result caps or pagination.

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?

Front-loaded with the resource and ordering, then provenance, then filters, then empty-state — a sensible order. The witness-verification clause is dense and long, but it carries the tool's core reliability contract rather than 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?

With no output schema, the description compensates by enumerating the capsule fields, and it also explains verification provenance, optional filtering, and empty-result behavior. An agent has enough to call it and interpret the response without further lookups.

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 both `since` and `section` (with its theme-slug explanation and pointer to list_sections/list_coverage) are already fully documented. The description only restates the filters at a high level ("on/after a date or within one section") without adding syntax or defaults, so the baseline 3 applies.

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?

States a specific resource and shape: "Recent dated price-change capsules, newest first," plus the fields each capsule carries (vendor, plan, before→after, date, sources). It is clearly a changelog feed, but it never distinguishes itself from near-siblings like price_movers or get_price_history, so an agent must infer the boundary.

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?

Usage is implied by "recent ... newest first" and the two optional filters, but there is no explicit when-to-use statement and no exclusion against overlapping siblings (price_movers, most_volatile_in_category, get_price_history). The only positive guidance is the empty-result note, which sets expectations rather than routes the agent.

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