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

Annotations only declare readOnlyHint=true, but the description goes further: it names the underlying endpoint (GET /tax_rates/calculate), confirms no record is created, and enumerates the response fields including the status enum values (taxable|non_taxable|not_registered|reverse_charge). That is substantive behavioral context an agent cannot get from the annotations alone.

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-loaded with purpose and read-only status before the endpoint and return shape. The response-field enumeration is long but earns its place because there is no output schema; still, it is the densest part of an otherwise tight definition.

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 13 parameters, no output schema, and only a readOnlyHint annotation, the description compensates fully: it covers purpose, side-effect profile, endpoint, and the return contract including status values. 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%, so the baseline is 3. The description adds framing beyond the schema by tying inputs to jurisdiction logic ('VAT / GST / US sales-tax rules per jurisdiction'), which implicitly explains why location fields (street, city, postal code) matter, though it does not document individual parameters.

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 ('Calculate the correct tax rate/amount for a sale') plus the inputs it depends on (customer location, product). It is unmistakably distinct from the CRUD siblings like quaderno_create_transaction, which merely record a sale rather than compute tax.

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?

Explains the context of use ('for a sale given the customer's location and product') and explicitly clarifies 'READ-ONLY (no record is created)', which steers an agent away from the create_* siblings. It does not name a specific alternative tool, so it falls short of a full when/when-not routing statement.

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