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

With readOnlyHint=true already covering safety, the description adds meaningful behavioral context: it returns exactly 5 items, uses compact fields, sources from a specific domain, is CC0-licensed, and has personal contact data removed. This goes beyond the annotation and helps an agent understand limitations and data handling.

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 description is compact and front-loaded: 'FREE' immediately signals cost/sample nature, followed by what is returned, the optional filter, and data licensing. Every clause adds useful information without redundancy.

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 simple, optional-parameter read-only tool, the description covers most operational basics: source, item count, filter option, and data licensing. However, with no output schema, 'compact fields' is vague and an agent cannot know which tender fields will be returned, which is a real gap for deciding whether this tool satisfies a request.

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 the cpv parameter as a CPV code or prefix. The description adds 'optionally filtered by one CPV code' and 'prefix', which reinforces optionality, but does not provide substantial meaning beyond the schema's pattern and examples.

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 clearly identifies the resource ('German public calls for tenders'), the source ('oeffentlichevergabe.de'), and the scope ('5 most recent', 'compact fields'), making the tool's purpose understandable. It is distinguishable from siblings like search_tenders and tender_stats through the 'sample' framing, though it lacks an explicit verb such as 'list' or 'retrieve'.

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 states that filtering is optional but gives no guidance on when to choose this tool versus search_tenders, get_tender, or tender_stats. The word 'FREE' implies a low-cost/sample use case, but this is not explicit and there are no stated exclusions or alternatives.

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