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

The single word 'Writes' plus the note that closing 'runs a conversion engine' discloses a meaningful behavioral fact beyond the annotations: this call has no conversion side effects, unlike the close endpoint. Annotations only give openWorldHint=false and destructiveHint=false, so the added context about side-effect-free mutation is real value. It does not cover permissions or partial-update merge semantics, keeping it from a 5.

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, no filler, and the scope statement is front-loaded before the exclusion. Every clause either defines the mutation surface or routes the agent elsewhere.

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?

An output schema exists, so return values need no explanation, and annotations cover the safety profile. What remains thin is the field inventory for a 0%-documented nested object and the unaddressed status field, which is the one place an agent could misfire.

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% on a nested round object with ~15 fields, so the description carries real burden; it names four of the updatable fields (name, target, valuation, dates) but ignores the required nested id/companyId UUID wrappers and most numeric fields (optionPoolPct, pricePerShare, totalRaiseTarget). The schema exposes a 'status' field while the description says the round is not moved between open and closed, which leaves the meaning of that field ambiguous.

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?

A specific verb + resource ('Changes a funding round's own terms') plus an enumerated scope (name, target, valuation, dates) tells the agent exactly what is mutated. The closing sentence separates it from the close/reopen endpoints, so the agent can distinguish it from cap_table_close_cap_table_round and cap_table_reopen_cap_table_round without opening a schema.

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 states when NOT to use it: moving a round between open and closed goes through a separate closing call (with a conversion engine) and a separate reopening call. The guidance is clear but stops short of naming those sibling tools by name, leaving the agent to match 'has its own call' to the correct sibling.

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