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

With no annotations, the description carries the full burden and does so well: it discloses the return artifact (members.27aday.com/go URL), the one-time ticket bound to the caller's API key, the read-only nature ('no purchase or account action happens here'), the cost/auth model ('Free with a key'), and a failure mode ('May return 503 when disabled'). This is unusually rich behavioral context for a no-annotation tool.

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 purpose, then parameter provenance, then return value, then constraints and failure mode. Each sentence carries distinct information (link nature, ticket/API key, retailer handoff, cost, 503), with no redundancy.

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 correctly compensates by describing the returned URL and its ticket semantics. Auth expectations (API key), cost, side-effect boundary, and a failure case are all covered, leaving nothing essential an agent needs before invoking it.

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 50% (source_id documented, source_kind's enum values only in the schema). The description adds provenance meaning beyond the schema by explaining both parameters come from the offer's source ids in get_verified_offer(s), which is the key semantic an agent needs to supply valid values.

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+resource ('Tracked 27aDay buy link for one marketplace source') and immediately scopes the input to a single marketplace source. It distinguishes itself from siblings by tying source_kind/source_id explicitly to get_verified_offer(s), so an agent can separate it from compare_prices, get_current_prices, get_product, etc.

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 establishes the prerequisite chain ('source_kind and source_id from get_verified_offer(s), the offer's source ids') and tells the agent what to do with the result ('hand it to the shopper unchanged'). It does not name an explicit alternative tool or state when this should be skipped, but the workflow context is clear.

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