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

Annotations only declare the mutation profile (non-readonly, non-idempotent, non-destructive); the description adds substantive behavior beyond that: the returned trial_code, the quota semantics (5 unique Dutch addresses, 10 with the user's own e-mail), the once-per-conversation limit, and the two preconditions that suppress the call entirely.

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?

Three dense sentences, front-loaded with purpose, then limits, then routing and exclusions. No filler and nothing restated from the title or schema.

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?

There is no output schema, so the description carries the return-value burden and does so by naming trial_code and telling the agent exactly which tools consume it. Combined with the quota and precondition details, an agent has everything needed to call this 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% and the schema already says the e-mail is optional and must not be invented, so the baseline is 3. The description adds real meaning the schema does not: supplying the user's own e-mail doubles the address quota from 5 to 10, which explains why the agent should surface the option.

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 (starts), resource (free Wozapi trial), and output (returns a trial_code) in the first sentence. It is clearly distinguishable from siblings like add_trial_email, create_credit_payment_link, and lookup_woz_value, which are all downstream or parallel concerns.

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?

Gives explicit when-to-use routing (pass trial_code to lookup_woz_value and start_address_list) and explicit when-not conditions (once per conversation, not when the user is signed in, not when the connection already has a Wozapi API key). This is about as complete as usage guidance gets.

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