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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuine behavioral context the annotations do not: the conditional "when the API includes them" warns the agent that rules may be absent from the response, which prevents misinterpreting an empty rules array.

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?

One front-loaded sentence carrying the return-shape information, followed by the REST endpoint mapping. The trailing "GET /security-group/{id}" is arguably redundant with the tool name but is short and harmless.

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 correctly compensates by enumerating the return fields and their sub-fields, which is exactly what an agent needs to plan parsing. Missing only pagination/error behavior and any note on the zone parameter's default.

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 both id and zone are documented in the schema itself. The description adds no format or constraint detail beyond that, so the baseline 3 applies.

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 ("Details of one security group") and enumerates the returned fields (description, external sources, rules with protocol/ports/network/direction). It distinguishes itself from the plural sibling exoscale_list_security_groups implicitly via "one security group", though it does not name that sibling explicitly.

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 singular scope implies lookup-by-id usage versus the list sibling, but there is no explicit when-to-use guidance, no statement of prerequisites (zone selection), and no exclusion of alternatives. Usage is inferable but not stated.

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