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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds genuinely new context: the uniform-start assumption, the fact that unspecified values are reported in `assumed`, and what the answer will contain. It doesn't discuss runtime behavior such as how long a 500-fill scan takes or error conditions, keeping it at a solid 4 rather than 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?

Purpose is front-loaded in the first sentence, and the examples plus answer-format sentence follow logically. There is mild redundancy in stating the uniform-start assumption twice (in the preamble and again in the answer instruction), and the response-format sentence is long, but nothing is wasted.

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?

For a 25-parameter tool with no output schema, the description compensates by spelling out the returned content (fill count, limiting bank, resulting pressures, why one more fill fails) and by instructing the follow-up offer. That covers the main gaps; it still doesn't mention error handling or how the `assumed` fallbacks should be surfaced to the user beyond a brief note.

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 100% across all 25 parameters, including the critical note on start_pressure, so the schema already carries the semantics. The description only adds that start_pressure and the mix define the assumed tank start; that is marginal over what the schema documents, so the baseline 3 applies.

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 opening sentence states a specific verb, resource and scope: counting how many identical fills the source banks can supply before one can't supply the next. It also gives the stopping condition (bank hits min pressure, or can't decant high enough without a booster), which cleanly distinguishes it from siblings like decant (which plans the transfer itself) and gas_usage.

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?

It supplies concrete trigger phrasing in two languages ("how many tanks can I fill with NX32", "how many trimix fills can I make", "koliko boca mogu napuniti"), so an agent can match user intent reliably. It never names a sibling alternative or a when-not-to-use case (e.g. when the user actually wants the decant plan, use DIVESOFT_REAL_GAS or decant), so it stops short of a 5.

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