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

With no annotations, the description carries the full burden, and it does much of it: it discloses cost ('Free'), the negative return boundary (no toll numbers), and that freshness metadata is included. It does not cover auth needs, format, or pagination, but for a zero-parameter read-only listing that is a reasonable disclosure level.

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 sentences with no filler; the output content is front-loaded and the critical boundary condition ('Returns no toll numbers') is stated before the upsell. Every sentence earns its place.

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?

No output schema and no annotations exist, so the description must explain returns, and it does so qualitatively (venues, toll-bearing status, freshness). It is complete enough to call correctly; only exact return shape is left unspecified, which is acceptable for a simple list tool.

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?

The input schema has zero properties, so per the rubric the baseline is 4. Nothing in the description contradicts or obscures the empty parameter set.

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 ('List the trading venues this service covers') plus the two attributes returned (toll presence, reading freshness). It also explicitly separates itself from its only sibling by noting it returns no toll numbers and that 'the measurement is the paid tool,' i.e. get_toll.

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?

Clearly signals this is the free discovery tool and that measured toll values come from the paid sibling, which gives an agent a strong routing rule. It stops short of an explicit 'call get_toll when you need actual numbers' instruction, so it is context rather than full guidance.

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