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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the bar is lower. The description adds 'Live', signalling counts are current rather than cached/snapshot, and specifies the aggregation granularity (total, per metro, per category) — useful behavior beyond the annotations. It stops short of noting refresh cadence or whether counts include inactive businesses.

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?

Two short sentences, front-loaded with what is returned and followed by the use case: scope first, purpose second, no filler or 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 no-input, no-output-schema tool this is complete enough: it names the dimensions of the returned aggregation so an agent knows both that no parameters are needed and what data comes back.

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?

Zero parameters, so the baseline is 4. The description correctly implies the tool takes no filters, with counts pre-aggregated across the whole directory rather than scoped by city or category input.

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: 'Live listing counts for the whole Ni Biashara directory: total, per metro area and per category.' This is clearly distinguishable from siblings search_directory and get_business, which return listings/entities rather than aggregate counts.

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?

'Useful for sizing diaspora business communities by city or sector' implies a use case but gives no explicit when-to-use versus alternatives, no when-not-to-use, and does not name search_directory or get_business as alternatives.

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