list_lookalike_reports

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

Annotations only declare readOnlyHint=true; the description adds substantial behaviour the agent could not otherwise know: newest-first ordering, reports exist even for alert-free months with per-source coverage figures, and a non-subscriber gets an empty page rather than a 404. It also discloses the auth/setup requirement, which is exactly the kind of context annotations cannot carry.

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 short sentences front-load the resource and ordering, then cover the empty-month case and the empty-page edge case, followed by a clearly labelled ACCESS block. No sentence is redundant and the actionable setup steps are stated plainly.

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?

An output schema exists, so return-value detail is unnecessary; the description instead covers what the schema cannot — empty-result semantics, non-subscriber behaviour, and access prerequisites. Nothing an agent needs in order to call this correctly appears to be missing.

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% for both parameters (page, limit) with bounds, so the schema does the documentation work. The description says nothing about pagination behaviour, defaults, or how 'newest first' interacts with paging, so it adds no meaning beyond the schema — baseline 3.

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 ('List the monthly Lookalike Watch reports') plus ordering ('newest first'). The line 'A month with no alerts still has a report' also implicitly separates this from list_lookalike_alerts, so an agent can distinguish the two without opening either schema.

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 clear preconditions (needs a Proof account, PROOF_API_KEY set, server restart) and explicitly rules out an alternative auth path: 'start_login does NOT open this tool.' What's missing is a positive statement of when to choose this over the alert-level sibling, but the context provided is strong for the access decision.

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