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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the description's real contribution is provenance ('SEC Form D and newswire funding announcements') and the important caveat 'coverage is partial'. That caveat is genuinely useful for interpreting results, though it doesn't quantify the gap or mention pagination.

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?

Two sentences, zero filler, with the core capability front-loaded and the coverage caveat held to the end where it belongs. Every clause earns its place.

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 an output schema present, return-shape details are unnecessary, and the description supplies the provenance and coverage caveat an agent needs to judge result trustworthiness. It could say more about how partial the coverage is or whether results are paginated, but nothing essential is missing for correct invocation.

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%, so all five parameters (limit, stage, sector, date_to, date_from) are already documented in the schema. The description only gestures at the filter axes and adds no syntax or semantics beyond what the schema provides, so the baseline 3 applies.

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 ('Search') and resource ('financing rounds') plus the three filter axes (sector, stage, date window), so the resource is clearly distinct from siblings like vc_search_investors and vc_search_people. It never explicitly names an alternative tool, so it falls short of the sibling-differentiation bar for a 5.

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 phrase 'answers "funding rounds this week/quarter"' gives a concrete use context an agent can match against an intent. There are no exclusions or named alternatives, so it stops short of the when-not guidance a 5 requires.

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