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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds essentially nothing beyond that: it is silent on duplicate handling (what happens if a partner surcharge already exists for that pairing), required permissions, or side effects on pre-invoicing despite the useInPreInvoicing flag.

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 compact sentences, front-loaded with the core action before the optional-scope qualifier. Nothing is wasted or buried.

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 9 parameters (4 required), full schema coverage and no output schema, the essentials are technically present. However, for a mutation tool the description omits conflict behaviour, the relationship between amount, carrierRateExVat and marginType, and VAT handling — gaps an agent would want filled before writing data.

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 the baseline is 3. The description's only parameter remark — that organisationId makes the surcharge customer-specific — largely restates the schema's own description of that field, adding no new syntax or interaction detail.

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 ('Add') and resource ('partner surcharge price for a carrier surcharge on a contract'), which is distinct from AddPartnerRate and GetPartnerCarrierSurcharges. It does not explicitly name the sibling to avoid (e.g. UpdatePartnerSurcharge), so differentiation is inferable rather than stated.

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 clause 'Optional organisationId makes it customer-specific' hints at when to supply that field, but there is no explicit guidance on when to use this versus UpdatePartnerSurcharge or AddPartnerRate, nor any prerequisite about the contract or surcharge catalog needing to exist.

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