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

Annotations already declare readOnly/idempotent/openWorld, so the safety bar is low, and the description adds genuinely non-obvious behavior: every part is attributed to its source and empty parts explain themselves (partial-result semantics). It doesn't hint at cost or latency, which matters for a multi-source aggregation call.

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 tight sentences, front-loaded with the core promise and followed by the optional-input conditions and the result contract. No filler and no repetition of the tool 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, and the description does most of the work by naming the sections returned and how empty sections are reported. What's missing is any sense of result shape/size or whether parts can be selectively requested, which for a broad aggregation tool would help an agent decide whether to call it or a narrower sibling.

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 100%, so the schema already explains that name+country unlocks the register and ticker unlocks SEC revenue. The description restates those couplings without adding format, fallback, or precedence rules (e.g. what happens if name/country combination is invalid). Baseline 3 is right.

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+scope: everything public about one company, keyed off its domain, and enumerates the returned parts (registrar, DNS, email provider, tech stack, hiring with roles/salary/timing). The enumeration is what distinguishes it from its many narrow siblings like domain_lookup, detect_tech_stack, and list_open_jobs — it is the aggregate view.

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?

"Add name and country for the official register entry, or ticker for SEC figures" gives useful enrichment conditions, but there is no guidance on when to call this versus siblings — notably company_search for when you don't already have a domain, or the narrower tools when only one part is needed. Usage is implied, not stated.

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