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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds the default sort order ('neueste zuerst'), which is genuinely useful behavioral context, but stays silent on page size, total counts, and what happens when filters match nothing.

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 short telegraphic sentences, front-loaded with the action and ordering, then filters, then special modes. Little waste, though restating the status enum values duplicates the schema and could be dropped.

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 zero-required-parameter list tool with no output schema, the description covers ordering, filtering, incremental sync, and sparse fieldsets — enough to call it correctly. The main residual gap is pagination/return shape, which is only hinted at indirectly through the schema's '500 je Seite' note.

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 only 40%, so the description must carry weight: it names all five parameters and explains the intent of updated_since ('nur Geänderte') and fields ('nur IDs'). But customer_id and external_reference are only listed with no semantic explanation (match type, exact vs partial), and the status enum values merely repeat 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?

States a specific verb+resource ('Mietverträge auflisten') and adds a meaningful scope detail: default ordering 'neueste zuerst'. This clearly separates it from single-record siblings like get_contract or mutating ones like create_contract, though it never names an alternative explicitly.

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?

It enumerates the available filters and hints at two special modes ('mit updated_since nur Geänderte, mit fields nur IDs'), which implies when those modes are useful. However, there is no explicit when-to-use/when-not guidance versus get_contract for a single record, or any statement about pagination-driven iteration.

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