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

No annotations exist, so the description carries the full burden; it does disclose two real behavioral traits — the 100-item cap and the 'PRO' subscriber requirement (reinforced by access_token in the schema). It omits what 'resolve' returns, error behavior for oversized input, and whether lookups are billable, leaving meaningful gaps.

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?

Two short sentences with the key constraint front-loaded and no filler. The bare 'PRO.' fragment is terse to the point of being cryptic about what tier gating actually entails.

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 annotations and no output schema, the description is the only source of truth, yet it never explains what resolution returns (coordinates, timezone, address?) or how partial failures are reported. For a batch tool this leaves an agent unable to set expectations for the response.

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 only 50%; access_token is documented in the schema, and the description usefully characterizes postal_codes as Canadian postal codes or FSAs capped at 100. That is adequate compensation but adds nothing about format tolerance, deduplication, or ordering of results.

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 ('Resolve'), the resource (Canadian postal codes / FSAs), and the batch scope (up to 100 at once), which distinguishes it from the single-code sibling postal_lookup. It does not explicitly name the sibling it differs from, so it stops short of a 5.

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 phrase 'up to 100 ... at once' implies this is the bulk path versus the single-lookup siblings, but the description never states when to prefer batch_postal over postal_lookup or what to do with fewer/more than 100 codes. Usage is inferable rather than stated.

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