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

With no annotations supplied, the description carries the full behavioral burden; 'Arithmetic only' usefully discloses that nothing is persisted or fetched, and it states what is returned ('the counterpart plus concentration and mcg per unit'). It does not describe failure behavior, invalid combinations, or whether the result is rounded, which matters for a numeric calculator.

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?

Four tight sentences, front-loaded with the core action, followed by strength input options, direction, and return value. No filler or restatement of the tool name.

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 an 8-parameter, zero-required calculator with no output schema, the description covers the main input path and states what the return contains. The main hole is the syringe parameter's role, which an agent must infer from enum strings alone.

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 only 38% across 8 parameters, so the description must compensate. It does explain the conc_mg_ml vs vial_mg+water_ml alternative and the direction/dose_unit choices, but leaves the syringe enum (u100-0.3, u40-1.0, etc.) completely unexplained even though the syringe type governs units-per-mL arithmetic. Partial compensation only.

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 set: 'Convert between a dose (mg or mcg), syringe units and mL at a known strength,' which tells an agent exactly what computation is performed. It does not name or contrast any sibling (e.g., calc_reconstitute), so it falls short of the 5 bar for sibling differentiation.

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 gives implicit usage guidance by explaining the two direction modes and how strength may be supplied, and 'Arithmetic only' signals this is a pure calculator with no data lookup. However, it never states when to prefer this over calc_reconstitute or how to handle ambiguous inputs.

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