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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds meaningful context beyond them: it is the source of truth that `bun run plans:sync` regenerates plans.json from, and Stripe IDs are conditionally withheld. It doesn't discuss pagination or whether the catalog can be empty for unconfigured apps.

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 what is returned, then why it's authoritative, then the one flag caveat. No filler, and the most decision-relevant fact (source of truth) is placed high.

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?

No output schema exists, so the description's enumeration of returned fields (tiers, names, prices, trial, limits) does the work of explaining the response. The remaining gap is app_id acquisition — pointing to list_apps would make it fully self-sufficient for a 2-param tool.

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?

With 0% schema description coverage the description must compensate, and it does explain one of the two parameters precisely (Stripe price/product IDs omitted unless include_stripe_ids is set). app_id is only implied as "an app's" — no format or source-of-valid-IDs guidance — leaving the required parameter under-specified.

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 verb ("Download") and resource ("an app's live plan catalog") and enumerates the payload: tiers, names, prices, trial, and limits. It is clearly a read-only catalog listing, distinguishable from the many mutate-plan siblings (update_plan_*, archive_plan) and from list_apps.

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?

Gives real selection guidance — "diff against this rather than trusting the committed file" tells the agent to prefer this over plans.json, which is a concrete when-to-use rule. It stops short of naming sibling tools (e.g., list_apps for app_id discovery) or stating exclusions, so it is clear but not fully routing.

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