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

With no annotations, the description carries the behavioral disclosure burden. It does state that the tool performs an immediate calculation, proposes alternatives, and is browser-based. However, it does not explain limitations, assumptions, or what happens after calculation, leaving some behavioral ambiguity.

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 a single, well-structured sentence that leads with the core function (immediate calculation), adds the differentiator (alternative proposals), and notes the platform (browser-based). Every element earns its place with no redundant content.

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?

Given the tool's simple nature (zero parameters, no output schema), the description adequately covers the subject, primary action, and a secondary feature. It does not explicitly describe the output format, but the return value is reasonably inferable from the stated calculation and proposal behavior.

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?

The tool has zero parameters, so the schema fully covers parameter semantics. The description correctly adds no parameter information; the baseline score of 4 applies because there is no need for additional parameter-level explanation.

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 clearly states the tool's purpose: it calculates the cost increase from the October 2026 postal rate revision and proposes alternative services. This specific scope distinguishes it from sibling tools like shipping-calculator, making the purpose immediately obvious.

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 description implies the intended use case—evaluating the impact of the October 2026 postal rate change and seeking alternatives—but provides no explicit guidance on when to use this tool versus other shipping-related tools, nor does it mention exclusions. The context is clear but underdeveloped.

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