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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false. The description adds valuable behavioral context: it names the specific return fields (earliest, latest, confidence, ready-to-show text) and discloses the edge case of returning an empty list when no carrier is enabled. It does not mention rate limits or auth, but the annotation coverage reduces the burden.

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 and return shape are front-loaded in a dense but efficient opening sentence, followed by a concise edge-case note and the endpoint. No sentence is wasted.

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?

With no output schema, the description appropriately explains the return structure and an important empty-list behavior. The only notable omission is preparation_time, which is covered in the schema, so the description is nearly complete for this read-only estimation tool.

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 80%, so the schema already documents most parameters. The description adds marginal meaning by indicating the optional courier restriction and service-level choices, but it does not mention preparation_time at all, leaving that schema-only. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

Specific verb 'estimate' and resource 'delivery dates', with added detail about per-service-level windows. It does not explicitly distinguish itself from sibling shippit_get_quotes, which could cause confusion for an agent choosing between the two.

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 explains what the tool does but gives no explicit guidance on when to prefer it over alternatives like shippit_get_quotes. It also lacks prerequisites or exclusions, leaving usage context implied rather than stated.

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