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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the underlying API mapping (GET /v1/campaigns/:id), but says nothing about auth requirements, 404 behavior for an unknown id, or what the returned campaign object contains.

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 very short sentences with zero waste, and the action is front-loaded before the API endpoint reference. Every clause carries information.

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?

A simple single-parameter read tool with no output schema, where annotations handle the read-only safety signal and the schema fully documents the id. The description covers the core operation adequately, with only minor gaps around failure behavior.

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 'campaign_id' is already documented as the campaign's UUID in the schema. The description contributes no additional syntax or format detail beyond confirming retrieval is by id, so 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?

The description states a specific verb and resource ('Fetch a single campaign') and scopes it with 'by id', which separates it from list_campaigns. It does not explicitly name the sibling it contrasts with, but the singular 'single campaign by id' makes the distinction inferable.

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 only implied: the phrase 'by id' signals this is the retrieval path when the campaign's UUID is known. There is no explicit statement of when to prefer this over rewardful_list_campaigns, and no mention of error conditions such as a missing or invalid id.

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