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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses latency (5-9 seconds), cost structure (5 credits, free on misses/errors/no-evidence), estimate-vs-fact semantics ('size, revenue and funding fields are estimates', missing evidence yields null), and where provenance lives (_meta.sources). These are operational traits an agent cannot get from the annotations or schema.

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?

Purpose and scope lead, then the field inventory, then routing, then the operational caveats (latency, estimation, cost) — a deliberate front-loading order. Five sentences, each carrying distinct information, with no filler or restatement of the name.

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 compensates by naming the returned fields and their reliability, and by explaining where sources are surfaced. Combined with the per-call cost and latency disclosure, an agent has everything needed to decide and invoke 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?

With a single parameter and 100% schema description coverage, the schema already carries the meaning; the description adds no extra syntax or constraint beyond what the schema's 'no path, no https://' note provides. Baseline 3 is appropriate for a fully documented single-param tool.

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 ('Returns a firmographic profile for one company from its domain') and enumerates the concrete output fields an agent will get. It also names exactly which sibling handles each adjacent job (search, contacts, tech), so the tool is distinguishable without opening any 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 an explicit positive trigger ('when you have a company domain and need to qualify or segment the account, especially GCC and MENA companies') plus explicit exclusions routed to the correct alternatives (apione_company_search, apione_people_search / apione_email_find, apione_tech_detect). Nothing about when-to-use is left to inference.

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