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

Annotations only declare readOnlyHint=false and destructiveHint=false; the description adds substantial behavioral context: 409 dedupe on same startup+series within 7 days, 5-credit cost, and a free-account requirement. These are operationally critical facts an agent cannot infer from structured fields.

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?

Dense, front-loaded, and every clause earns its place: ownership rule, format constraints, dedupe, cost, and account requirement. No filler, and the primary purpose leads.

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 should carry the burden, and it covers the high-risk facts (cost, dedupe, auth). It is slightly incomplete on the startup reference requirement (slug vs id) and the optional valuation fields, but overall sufficient for a submission tool.

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?

At 64% schema coverage, the schema already documents most fields (series vocab, USD amount, YYYY-MM-DD, third-person ≤1000 chars). The description largely restates these, only adding the ownership constraint on the startup reference. It does not clarify that at least one of startup_slug/startup_id must be supplied, nor cover the valuation params.

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 ('Announce a funding round for a startup you own'), which reads distinctly against read siblings like query_funding or get_startup_funding_history and other submitters like submit_exit_event. It does not name a specific sibling to disambiguate, but the resource is unambiguous.

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 ownership precondition ('created_by must match your API key user') implies when this tool is valid, but there is no explicit when-to-use vs alternative guidance (e.g., versus submit_exit_event or query_funding). Usage is implied rather than stated with exclusions.

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