US parcel shipping price index

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

Annotations already mark the tool as read-only, idempotent, and non-destructive, and the description adds valuable behavioral detail: reading spends no quote allowance, invalid month shapes return invalid_month, and missing issues return issue_not_found with available_months. It also states that every issue is directly comparable month-over-month, which is useful operational context.

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 dense but every sentence earns its place: definition, output, use case, alternative, and parameter rules are all front-loaded in a logical order. There is no filler or repetition.

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 read-only reference tool with one optional parameter and an output schema, the description covers purpose, use case, alternatives, parameter behavior, error semantics, and comparability. Nothing an agent needs to invoke it correctly is missing.

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%, but the description goes far beyond it: it specifies the YYYY-MM format, the default when month is omitted, the earliest available issue (2026-07), one-issue-per-month granularity, and the exact error responses for invalid or nonexistent months. This fully compensates for any ambiguity in the schema alone.

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 names a specific resource (SMKlog US parcel shipping price index), defines its scope (six boxes, 1-20 lb, Newark to five US cities), and states the output. It also distinguishes itself from get_parcel_quote, so an agent can tell them apart without opening schemas.

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 explicitly says this is reference data for questions like US shipping costs, notes that reading spends no quote allowance, and directs callers to get_parcel_quote for a specific shipment. This is clear when-to-use and when-not-to-use guidance with a named alternative.

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