Fetch what a user drank on their first/latest visit to each venue (opt-in)

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

Annotations only declare the operation is non-read-only, open-world and non-idempotent; the description goes far beyond that by disclosing cost ('costs API calls', one call per check-in), quota protection (~100 calls/hour, stops cleanly on 429 with stopped_for_rate_limit and rate_limit.resume_at), cache-diffing ('already-cached check-ins are never re-fetched'), and 404 memoization. It also scopes what is persisted ('stores only beer, brewery and date — never comments'), which is exactly the kind of mutation detail the annotations cannot 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?

Front-loaded with the two facts that gate the call ('OPT-IN, costs API calls') before any mechanics, and the remaining clauses cover distinct topics: prerequisite, scope limit, batching/rate limits, narrowing, and result location. Dense but every clause carries operational information an agent needs.

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 naming the exact result path (untappd_cache_has_visited -> matches[].drinks) and the control fields (stopped_for_rate_limit, rate_limit.resume_at, another_run_needed) an agent must branch on. For a mutating, rate-limited, cache-writing sync tool this covers everything needed to call and re-call it correctly.

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 venue_ids, which, max_calls and username are already documented with defaults and bounds. The description restates the same facts ('Narrow with venue_ids and which', 'at most max_calls per run (default 10, max 50)', 'Omit username for your own account') without adding format or edge-case semantics, so the baseline of 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 verb and resource ('fetch the FIRST and MOST-RECENT visit check-ins of each venue via checkin/view') plus the scope limit ('two check-ins per venue at most, never the full list'), which cleanly separates it from untappd_sync_checkins and untappd_cache_has_visited. The parenthetical '(opt-in)' in the title reinforces that this is not a general-purpose fetch.

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 an explicit prerequisite ('run untappd_sync_user_venues first'), a narrowing rule ('Narrow with venue_ids and which'), and an iteration protocol ('run again until another_run_needed is false'). It also names the downstream query for results ('untappd_cache_has_visited under matches[].drinks'), so the agent knows the full workflow.

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