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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the 'Read-only' sentence is largely redundant with structured data. The description does add one genuinely useful behavioral fact beyond annotations: the hard constraint that a campaign belongs to exactly one source and cross-source campaign_id values are refused downstream. Pagination behavior, default ordering, and result shape are not disclosed.

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?

Three short sentences with the scoping definition front-loaded and the write-consistency warning last. Minor waste: 'Read-only' duplicates the annotation, and the mixed-domain parentheticals ('ad set' vs 'job-board posting') add wording without adding precision.

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 list tool with 0% schema description coverage, no output schema, and four undocumented parameters, the description should cover pagination limits, the meaning of is_active, and what a returned campaign contains. It covers only the source_id relationship, leaving an agent unable to predict defaults or the response shape.

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 carries the full burden of explaining four parameters. It explains source_id (the key filter, and why it matters) but says nothing about limit, offset, or is_active — not even that is_active filters to active/inactive campaigns. Three of four parameters remain undocumented in both schema and description.

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 ('List placements INSIDE a channel') and anchors it to a concrete parent entity via 'a specific ad set, a job-board posting'. It also implicitly distinguishes itself from hr_list_sources by explaining that a campaign belongs to exactly one source. The only deduction is that it renames the resource from 'campaigns' (name/title) to 'placements', which costs a moment of reconciliation.

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?

It gives one concrete usage rule: read with the same source_id you intend to write with, since a cross-source campaign_id will be refused on application creation. That is real when-to-use guidance, but there is no guidance on when to pick this over the many sibling list tools (hr_list_applications, hr_list_sources, etc.), and no exclusions.

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