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

Annotations already declare readOnly, idempotent, closed-world, non-destructive behavior, so the safety profile is covered. The description adds meaningful context beyond them: 'current' signals live rather than cached data, 'public' signals no auth or private data is involved, and 'source URLs' discloses that provenance is returned. It stops short of stating freshness/caching or response ordering.

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?

A single sentence with zero filler; the action and scope are front-loaded and the enumerated resource list is dense with information. Nothing could be removed without losing content.

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 one-parameter, read-only tool with full schema coverage and no output schema, the description lists the returned data domains (plans, prices, currency, limits, models, source URLs), which carries most of the return-value burden. It does not describe response shape or nesting, a minor gap that does not block correct invocation.

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%, and the 'locale' parameter already documents its enum, default, and the no-fallback-to-another-market rule. The description's 'for a language edition' reinforces that intent but adds no format, syntax, or edge-case detail beyond the schema, so 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?

Uses a concrete verb ('Read') with a specific resource set: current public plans, prices, currency, limits, models, and source URLs, scoped to a language edition. An agent can immediately tell this is the single-market price/plan fetcher rather than a comparison or page reader. Sibling differentiation is only implied by the phrase 'for a language edition', not stated against compare_plans.

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?

Scope ('for a language edition', 'current public') implies when this tool applies, but there is no explicit when-to-use versus compare_plans or search_content, and no stated exclusions. The agent must infer that this is the single-locale lookup while compare_plans is the cross-locale alternative.

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