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

Goes well beyond the annotations by disclosing that a created form is immutable ('cannot be edited, so a later label needs a second form'), that it is side-effect-free in practice ('reaches no one and costs nothing'), and that it requires a Cotlet API key with app access. This adds real behavioral context for a non-read-only tool, though failure modes and rate limits are not covered.

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?

Front-loads purpose and output, then layers constraints; sentences are information-dense and mostly earn their place. The 'reaches no one and costs nothing / does not ask for your OK' clause is slightly chatty but conveys confirmation behavior.

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 still states the return is a PDF link, and it covers the auth requirement, immutability, and timing rules for a 3-optional-param mutation tool. Minor gaps around error/edge handling remain but the agent has enough to call it correctly.

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, but the description adds meaning to ship_date by explaining that it maps to the End of Day page's Ship Date group and that late labels roll to the next day, and clarifies batch_id scoping. It adds useful semantic context beyond the schema fields.

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?

States a specific verb (create) and resource (USPS End of Day SCAN Form), defines its scope (labels of one Ship Date) and its output (PDF link). An agent can distinguish it from siblings like buy_label or create_batch without opening the schema.

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?

Provides a scope exclusion ('Covers USPS labels only') and a timing rule (labels after 8:00 PM local belong to the next day), which imply when it applies. However, it never names an alternative tool or states when to prefer this over other Pirate Ship label/batch operations, leaving the routing decision to inference.

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