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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds the meaningful behavioral detail: results are verified addresses with provenance (page and date), and stale entries are flagged 'unverified' with a note. It does not say what an empty or unmatched query returns, but the verification-status semantics are genuinely additive.

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?

Four short sentences, front-loaded with the trigger condition, then result semantics, then scope, then the exclusion. Every sentence earns its place, though the coverage list and the exclusion could be tightened into one clause.

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?

Output schema exists and annotations cover the safety profile, so the description only needed to cover selection context and provenance semantics, which it does. The one gap is that all three parameters are optional yet the description never says what a call with no filters returns.

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 100%, so each parameter is already documented with examples and enum meanings; the description only implicitly echoes the query and country dimensions via the company-category and Austria/Germany lists. Baseline 3 applies when the schema carries the weight and the description adds nothing operational beyond it.

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 and resource ('returns verified postal addresses') plus what each result carries: the page where it was read and the date. It also scopes the domain (Austrian/German phone, energy, Rundfunkbeitrag, TV and fitness companies), which separates it from siblings like save_address, delete_address or list_letters.

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?

Opens with an explicit trigger ('Use this when a letter goes to a known company') and an explicit non-trigger, routing other recipients (landlord, insurer, authority) to the user's contract, order, invoice or recipient letter. Nothing is left to inference about when this lookup is appropriate.

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