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

With no annotations, the description carries the full behavioral burden. It does add two useful facts beyond the schema: the operation is read-only and it depends on a configured GeoIP database (a real failure mode). It says nothing about rate limits, accuracy caveats, or what happens when the database is missing, so coverage is partial rather than rich.

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 the core action and its outputs, then the prerequisite and read-only status. Every clause earns its place with no restatement of the tool name or filler.

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 single-parameter, no-output-schema read tool this is close to sufficient: it names the returned fields, the input flexibility, the read-only nature, and the database prerequisite. Only minor gaps remain, such as error behavior when no GeoIP database is configured, which keeps it from a 5.

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?

One parameter with 100% schema description coverage, so the schema already documents target as 'IP address or host name'. The description adds only the mild clarification that a host name is resolved before lookup, which is a small increment over the schema's own example. Baseline 3 is appropriate.

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?

Specific verb (geolocate) plus resource (IP/host) and an enumeration of what is returned: ASN, network organisation, city/country. An agent can immediately tell this is a geolocation lookup. However, it does not distinguish itself from siblings with overlapping scope such as geo_route, asn_prefixes, or ip_reputation, so it stops short of a 5.

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?

Usage is implied by the purpose (use when you need ASN/geo data for an IP), and one prerequisite is stated: a configured GeoIP database must exist. There is no explicit when-to-use versus alternatives, e.g. geo_route for routing paths or asn_prefixes for CIDR blocks, leaving the agent to infer routing between adjacent tools.

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