add_customer

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

No annotations are given, so the description carries the full behavioral burden. It does disclose two non-obvious traits: the record is enriched from the external ARES registry, and an existing record is not overwritten (effectively a no-op/skip rather than an upsert). It does not say what happens when the IČO is invalid or not found in ARES, nor whether any permission or connectivity is required.

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 short, front-loaded sentences with zero filler; the core action comes first and the non-overwrite caveat follows immediately. Nothing could be removed without losing information.

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?

An output schema exists, so return values need not be explained, and the ID scheme and ARES sourcing are covered. For a mutation tool with no annotations, though, a brief note on failure behavior (missing/invalid IČO, unreachable ARES) would close the remaining gap.

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 all three parameters (ico, email, customer_id) are already documented in the schema, including the ARES enrichment note for ico. The description only reiterates the IČO/ARES linkage and adds no semantics about the format or constraints of customer_id or email beyond the schema.

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?

Uses a specific verb ('Přidá') and resource ('odběratele do adresáře') and names the mechanism ('podle IČO, data z ARES'), which clearly separates it from read-side siblings like list_customers or lookup_company. It stops short of explicitly naming the sibling it replaces, so a 5 isn't warranted.

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?

'Existující záznam nepřepíše' gives an important usage constraint — calling it for an already-present customer is a no-op rather than an update. However, there is no explicit statement of when to choose this over lookup_company (read ARES data) or how to then modify an existing entry.

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