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

The annotations already declare this as a read-only, idempotent, non-destructive operation. The description only adds 'Returns converted mass' and a pointer to list_bundles, which is minimal behavioral context and partly redundant with the output schema. No contradiction is present.

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 purpose is front-loaded, but the description spends sentences restating schema-level details ('Inputs: value, from, to' and 'Returns converted mass') that are already covered by the input and output schemas. The list_bundles pointer is also only loosely relevant, so not every sentence earns its place.

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 simple three-parameter conversion tool, the description covers purpose, usage contexts, and output, and an output schema already exists to explain return values. The only notable gap is the 'tonne' versus 'ton' inconsistency, which could confuse unit selection.

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 the schema already documents value, from, and to fully. The description restates 'Inputs: value, from, to' without adding semantic meaning, and its unit list uses 'tonne' while the schema enum uses 'ton', a minor mismatch that does not improve clarity.

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 uses a specific verb and resource: 'Convert weight/mass between kg, g, mg, lb, oz, st, tonne.' It names the domain clearly enough to distinguish it from sibling conversion tools such as convert_volume or convert_temperature.

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 clear usage contexts: 'Use for cooking, shipping, or fitness.' That helps an agent decide when this tool is appropriate, though it does not explicitly exclude other conversion tools or name a specific alternative beyond the vague pointer to list_bundles.

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