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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the agent knows this is a pure, side-effect-free computation. The description adds essentially nothing beyond that — no note on units returned, rounding, or that it is deterministic — so it earns only baseline credit given the annotation coverage.

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 short sentences, front-loaded with the action and its input, with no filler. The trailing list_bundles cross-reference is mild but arguably unnecessary padding for a self-contained calculator.

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 two-parameter deterministic calculator with full schema descriptions and an output schema, the description covers what is needed to invoke it correctly. Nothing essential is missing, though it offers no hint about the result's unit or magnitude.

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% and both parameters (speed_mbps, file_size_gb) carry their own descriptions with positive-only constraints, so the schema does the heavy lifting. The description only obliquely references 'connection speed' and adds no unit or format detail beyond the schema.

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 ('Calculate file transfer time') plus the key input condition ('at a given connection speed'), so an agent can tell what the tool produces. Differentiation from the hundreds of calculate_* siblings is absent, however, apart from a generic pointer to list_bundles rather than a named competing tool.

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?

The one-line purpose implies the scenario (estimating download/upload duration), which is enough for an agent to recognize the use case. There is no explicit when-to-use/when-not statement and no named alternative, and the 'See list_bundles' sentence is discovery guidance rather than selection guidance.

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