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

Annotations already cover safety (readOnly, idempotent, closed-world), lowering the bar, and the description still adds a genuinely useful semantic caveat: rounds/per_currency/undisclosed count equity only while by_category covers all categories, so the category split can exceed the round count. This is non-obvious behavioral context that prevents misreading the numbers.

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 waste. The output scope is front-loaded, and the qualifier about equity-only vs all-category counting is placed as a clear 'Note:' where it matters most.

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, the description carries the burden of explaining the return shape, which it largely does by enumerating rounds, countries, per-currency totals, undisclosed, and by_category. It stops short of exact key names or empty-slice behavior, but is otherwise complete for calling the tool 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?

Schema coverage is 100%, so the four filter parameters are fully documented in the schema (date formats, slug/ISO handling). The description adds only the framing that filters define 'a slice' and does not elaborate on how from/to/topic/country combine. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

The description states a specific purpose: producing aggregate counts (rounds, countries, per-currency totals, undisclosed, per-category) for a filtered slice of the funding database. An agent can distinguish this aggregation tool from the list/search siblings, though it never names them explicitly. Clear but not sibling-routed.

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?

Usage is only implied via 'a slice of the funding database' plus the optional filter parameters. There is no explicit when-to-use or when-not-to-use guidance, and no pointer to alternatives like list_funding_rounds or largest_rounds for row-level data. Adequate but leaves routing to inference.

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