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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), yet the description adds genuinely new behavioral facts: billing is per active minute, rounded up, no minimum, and node preparation is not charged. This billing-model disclosure is exactly the kind of context annotations cannot convey.

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?

Front-loads the billing model, then the input modes, then edge cases. It is dense but each sentence carries information; structure is a single flowing paragraph rather than scannable segments, which slightly hurts readability.

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 should carry the return-value burden; it implies a single price or a comparison across all catalog configurations but does not state the result shape explicitly. Inputs, billing rules, and the node/nodes_count behavior are otherwise well covered.

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 baseline is 3, but the description adds cross-parameter meaning the schema does not: node label selects that node's rate vs. pricing every configuration when omitted, and nodes_count > 1 split frames evenly across identical nodes. The input-mode relationship between duration params and render params is also clarified.

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 and resource ('Price a rental') plus the billing lens it uses ('the way EvaFarm bills it'). The sibling tools (get_node, list_nodes, rental_guide, service_status) do node lookup, guidance, or status, so cost estimation is unambiguously distinct.

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?

Gives clear operational context for the two valid input modes (a duration in hours/minutes, or a render via frames × seconds_per_frame) and explains what happens with vs. without a node label. It does not name an alternative tool or state any when-not condition, but no real alternative exists among the siblings.

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