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

With no annotations provided, the description carries the full behavioral burden. It usefully discloses that the tool is free and deterministic, but it does not explain the return format, the sign convention (to-minus-from or vice versa), or what happens with malformed timestamps.

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 description is two tight sentences with zero filler. The key purpose is front-loaded, followed by the free/deterministic qualifier and access methods.

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 utility with no output schema and no annotations, the description omits important context: what exactly is returned (days vs. seconds vs. both), how the result is chosen, and why both parameters are optional in the schema. The free/deterministic and HTTP endpoint details help, but the core return behavior remains underspecified.

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%, so the schema already documents both parameters with ISO-8601 examples. The description adds no additional parameter-level meaning, such as expected formats, timezone behavior, or how the optional 'from'/'to' parameters are handled when omitted. Baseline 3 is appropriate.

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 states a specific verb and resource: compute the difference between two ISO-8601 timestamps, with output units named (days/seconds). This clearly distinguishes it from all sibling utilities, which handle unrelated resources like encoding, hashing, and blockchain snapshots.

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 tells the agent it can be used over MCP or via an HTTP POST endpoint, and calls itself a deterministic micro-utility. However, it gives no explicit when-to-use guidance, no exclusions, and no alternatives to weigh against.

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