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

Annotations already declare readOnly and openWorld, and the description adds context beyond them: the risk of large result sets and a concrete note on how outputs feed buildConnectionString. It doesn't describe pagination or auth requirements, but adds meaningful behavioral context on top of 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?

Two tight sentences with the core scope and filtering cue front-loaded, followed by output/consumer notes. No wasted phrasing; the docs reference is compact. Slightly dense with references but all sentences earn their 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?

With no output schema, the description compensates by explaining the return value (each city's extract_parameter for buildConnectionString's city) and pointing to docs for full fields. Given 3 fully documented params and readOnly/openWorld annotations, this is nearly complete; only pagination/limits details are absent.

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 coverage is 100%, so the baseline is 3. The description still adds value: it explains why to use 'search' (city lists can be large) and reiterates the region_code provenance from searchGeoRegions, giving semantic motivation the schema alone doesn't fully convey.

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 (search) and resource (cities) plus scope (within a country, optional region). It distinguishes itself from sibling tools by referencing searchGeoRegions for the region_code and buildConnectionString as the consumer of its output, so an agent can place it in the geo lookup chain without ambiguity.

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?

Gives a clear usage cue: 'Use search to narrow results — city lists can be large,' and directs the agent to searchGeoRegions to obtain the region_code. It lacks explicit when-not alternatives (e.g., versus searchGeoZips/searchGeoISP), so it stops short of full exclusion guidance.

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