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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds one genuinely new fact — that the response includes template variables — which hints at the payload shape. It does not explain error behavior for bad IDs or what happens when both/no identifiers are supplied.

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?

A single front-loaded sentence with the read-only marker, the resource, both accepted identifiers and the payload content — zero filler and nothing buried.

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 simple read tool with full annotation coverage, the essentials are present. But with no output schema and 0% parameter description coverage, the description leaves open the practical question of which identifier is mandatory and what the returned 'template variables' look like.

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 0%, so the description must carry semantic weight; it does name both parameters and signals via 'or' that they are alternative lookups, which is real information beyond the bare anyOf types. However, it never states that at least one identifier is required, nor the expected format of sms_campaign_uuid.

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 ('[read] One SMS campaign') and disambiguates from list-style siblings by emphasizing 'One'. It also names the payload ('with its template variables'). It doesn't explicitly name list_sms_campaigns as the alternative, so it stops short of 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?

The singular framing implies retrieval of a single known campaign, which is the natural counterpart to list_sms_campaigns, but no when-to-use/when-not statement or prerequisite is given. Guidance is inferable rather than explicit.

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