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

Annotations declare non-readonly, open-world, non-idempotent, non-destructive, and the description adds two things annotations cannot: the API key is returned, and the agreement is permanently 'sealed into the chain.' It does not address re-invocation behavior (whether a duplicate call creates a second account) or auth requirements, so it falls short of a 5.

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 short, front-loaded sentences with no filler; purpose comes first, then the gate, then the side effect. 'Seals the agreement into the chain' is slightly jargon-heavy but conveys a real consequence.

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 7-parameter mutation tool with annotations and no output schema, the description covers the essential workflow, return value, and precondition. It omits guidance on the optional billing-related fields (devices, product), which is a minor gap given the schema describes them.

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 43%, so the description carries extra burden, and it does clarify the intent behind the two gating fields (terms_version tied to sebbi_terms, customer_agreed tied to the customer's verbal consent). However, it never mentions name, company, devices, or the product enum, leaving four optional parameters to 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?

States a specific verb and resource ('Open a sebbi.pro account') plus the concrete deliverable ('return their API key'), which an agent cannot get from the title alone. It is clearly distinguishable from siblings such as sebbi_terms or sebbi_overview.

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?

Explicitly gates invocation: 'Only call after showing sebbi_terms and the customer saying yes.' This names the prerequisite sibling tool and the human-confirmation condition, leaving nothing to inference about sequencing.

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