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

Annotations already declare readOnly/openWorld/non-destructive, so the safety profile is covered. The description adds meaningful context beyond that: it discloses the return fields (ID, name, price), the requirement that every invoice line must carry an article, and the auth prerequisite (Cotlet API key with app access). These are genuine behavioral facts not derivable from annotations.

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?

The core purpose is front-loaded in the first sentence and the return fields follow usefully. However, the middle sentences about revenue groups that "cannot be created in SnelStart Web" are tangential to a search operation and read as workflow lore that belongs with the invoice-line tool rather than here, diluting focus.

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 no output schema, the description correctly compensates by naming the returned fields, and it discloses the auth requirement and the business constraint that drives usage. For a two-parameter read tool this is close to complete; only explicit result-ordering or empty-match behavior is left unstated.

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 schema fully documents both query ("part of the article name") and limit ("records per page, default 50"). The description echoes "by name" but adds no syntax, matching behavior, or pagination detail beyond the schema, so the baseline of 3 applies.

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 ("Finds articles by name") plus the downstream purpose ("so an invoice line can use them"), clearly distinguishing it from sibling reads like snelstart_list_ledger_accounts or snelstart_list_customers. An agent can identify it as the article-lookup tool without opening the schema.

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?

Gives clear context for when to reach for it: articles are needed on every invoice line, even for hours or services. It doesn't name an explicit alternative or state when NOT to use it, so it stops short of full routing guidance, but the usage context is unambiguous.

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