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

With empty annotations, the description carries the full burden. It implies a read-only list operation but doesn't explicitly state side effects, error behavior, or what happens with an invalid country code. It does not contradict annotations, but it adds minimal behavioral context beyond the action itself.

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. It front-loads the primary action, then the optional filter, then a practical usage hint. There is zero wasted text and every clause 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 tool with one optional parameter and no output schema, the description covers the essential aspects: what it does, the filter, and how the result should be used. It does not detail the return format, but the reference to method ID in start-checkout hints at the output structure. Adequate for this complexity level.

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 baseline is 3. The description adds meaning by clarifying that the country parameter is an optional filter and specifies the ISO 2-letter format, which goes beyond the schema's brief description. It provides useful context for correct usage.

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 verb 'List' and the resource 'available delivery methods', and adds the optional country filter. It is distinct from all sibling tools, none of which deal with listing shipping methods, and it even cross-references start-checkout to show how the output is used.

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 usage context by noting the method ID is used in start-checkout, which tells the agent this tool feeds checkout. It doesn't explicitly state when not to use it, but no sibling tool offers similar functionality, so exclusions are unnecessary. The guidance is sufficient.

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