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

The description explicitly states 'Writes.' in a terse but clear manner, compensating for the absence of a readOnlyHint annotation. It also discloses a key behavioral trait: a new round starts OPEN and holds no capital, which is not apparent from annotations or the schema. This adds meaningful context about the tool's side effects. However, it doesn't mention any other side effects (e.g., whether it returns the created round verbatim), but given the output schema exists, that's less critical.

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?

The description is three sentences, each earning its place. The first sentence states the core purpose, the second is a minimal 'Writes.' that conveys an essential fact, and the third clarifies the initial state and scope. There is no fluff, and the key information is front-loaded. This is an excellent example of concise, structured description.

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?

Given the tool's complexity (a nested 'round' object with 13 fields, most undocumented in the schema), the description leaves the agent without guidance on what to supply. It doesn't explain the meaning of 'pastRound', the required 'companyId', or what fields like 'isPriced' or 'pricePerShare' represent. While the output schema exists, the input side is severely under-specified. The description could have provided field-level hints or examples, but it doesn't, making the tool hard to invoke correctly without external knowledge.

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 0%: the schema provides no descriptions for most fields (e.g., name, status, isPriced, optionPoolPct, etc.). The description does not compensate at all. It never mentions the 'round' object or its required fields, nor the 'pastRound' parameter. For an agent to correctly populate the complex nested round object, it would have to infer from field names, which is error-prone. The description adds zero value for parameter understanding.

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 opens with a specific verb and resource: 'Opens a new funding round'. It further explains what a round is ('the container investors and their agreements are attached to'), which is central to understanding the tool's role. It also explicitly distinguishes from close operations by stating 'It does not raise money or close anything', clearly separating it from sibling tools like cap_table_close_cap_table_round.

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 description clearly implies when to use this tool: when creating a new funding round. It adds 'It does not raise money or close anything: a new round starts OPEN and holds no capital until investors are added to it', which tells the agent not to expect this to handle investor additions or closing. While it doesn't name specific alternative tools, the negative statements effectively route the agent away from close/update tools. This is useful but not as explicit as naming a specific sibling.

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