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

Annotations only cover read-only/idempotent safety, and the description goes far beyond: it discloses the entitlement model (first 5 rows in full plus locked counts), field-level redaction (contact values and decision-maker names never returned), the OBSERVED-first ordering semantics, and that rows are never ranked by amount. This is unusually rich behavioral context.

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 row definition, then filters, then ordering semantics, then the sibling pointer, then access caveats. Dense and mostly earning its space, though the plan-promotion sentence and some access detail add length beyond the core selection need.

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 and nine loosely-described parameters, the description carries the full burden and delivers: row shape, ordering, filtering, entitlement limits, and redaction behavior are all covered. An agent can call and interpret this correctly without further context.

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 56%, so the description must compensate and largely does: it maps the filter set (investor, company, partner, stage, state, since-date, lead only) and crucially clarifies that `since` is the DFX observation date, not the round date. It leaves the DFX-id parameter family and limit/query syntax to the schema.

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 precise verb+resource (investor-by-investor participations in venture rounds) and enumerates the row contents (investor, company, fund, partner, role, new/follow-on, board seat, round type, stage, amount, source quote). It is unmistakably distinct from sibling list tools like search_vc_financings and search_vc_coinvestors.

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?

Explicitly routes to an alternative: 'For the largest rounds or raises in a period use search_vc_financings(since, order_by=amount).' It also names the filter conditions available, so an agent knows both when to pick this tool and when to pick the sibling.

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