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

readOnlyHint=true already covers the safety profile, so the description's job is to add context — and it does: default sort order, paging contract ('Returns total, next_start for paging'), and the meaning of the money fields including the currency distinction between sumCelkem/zbyvaUhradit and the *Men fields. That is real behavioral information not present in 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?

Three sentences, front-loaded with what the tool lists and its default ordering, followed by field semantics and the paging contract. Dense but every clause carries information; the money-fields sentence is the only one that could be tightened.

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 10 optional parameters, no output schema, and readOnly annotations, the description covers the missing pieces: return shape (total, next_start), pagination workflow, default ordering, and how to widen the returned field set. 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 description coverage is 100%, so the baseline is 3. The description does add genuine value by explaining the money-field semantics and the purpose of 'fields' for retrieving non-default properties, but it does not clarify the date filters, status enum, or search behavior beyond what the schema already documents.

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 ('List issued invoices') and disambiguates with the parenthetical 'sales invoices to customers', which separates it from abraflexi_list_received_invoices. It also declares the default ordering. It stops short of naming the sibling outright, so it is clear but not maximally differentiated.

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?

Filter semantics ('filtered by payment status, customer/supplier code, dates or text') imply when the tool is appropriate, and the status enum values are explained. However, there is no explicit guidance on when to prefer abraflexi_get_issued_invoice for a single record or abraflexi_list_received_invoices for the purchase side.

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