Search customers

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds meaningful behavioral context: it explains that nula.bg has no direct customer-creation API and that nula_create_invoice auto-creates missing customers. This helps an agent understand the system's behavior beyond the schema. It doesn't mention pagination or response details, but those are partially covered by the schema's page/limit/response_format parameters.

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 sentences with no filler. The core search capability is front-loaded, and the note about nula_create_invoice is a valuable addition that earns its place. Every sentence contributes.

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 read-only search tool with 100% schema coverage and no output schema, the description is nearly complete. It covers what the tool does, the search keys, and the key system constraint (no direct customer creation). The only minor gap is that it doesn't explicitly mention pagination behavior, but the schema's page/limit parameters already cover that.

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 schema already documents all five parameters. The description adds a little semantic value by grouping the search parameter as 'Name, EIK or VAT number' and mentioning 'get one by id', but it doesn't add meaning beyond what the schema already provides. Baseline 3 is appropriate.

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?

The description states a specific verb ('Find') and resource ('customers/counterparties'), and enumerates the search keys: name, EIK, VAT number, or id. It also distinguishes itself from the sibling create-invoice flow by noting that nula.bg has no direct customer-creation API, which helps an agent understand the tool's role in the broader workflow.

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 description clearly implies when to use this tool: when you need to find a customer by name, EIK, VAT, or id. It also gives a useful exclusion/alternative note: nula_create_invoice creates a missing customer automatically, so an agent knows not to expect a create-customer tool. It doesn't explicitly say 'use this instead of nula_lookup_company', but the search-by-EIK/VAT framing is enough context.

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