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 useful context beyond that by disclosing what the response contains (plan, handles, watched-source counts) and that it should be invoked before other tools. It does not address auth scope, pagination, or ordering of results, so it stops short of full behavioral disclosure.

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 sentences, zero filler: the first defines the resource and its fields, the second delivers the routing instruction. The most actionable sentence (call this first) is placed where an agent scanning for usage cues will find it.

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 input parameters and no output schema, the description carries the burden of explaining the return shape, and it does so by naming the per-brand fields. It is nearly complete for this complexity level; only result ordering/pagination and behavior on a single-brand or empty account are left unstated.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline of 4 applies. The description correctly frames this as an account-wide listing with no filtering arguments.

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 names the resource (the brands on the user's CueHQ account) and enumerates the payload fields an agent will get back (plan, handles, source count), which is far more specific than the bare name 'brands'. The retrieval verb is only implied rather than stated, but the contents are unambiguous and clearly distinct from siblings like list_cues or weekly_report.

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?

'Call this first when the user has more than one brand: the other tools take its brand_id' gives an explicit trigger condition plus the downstream reason, which effectively routes the agent before it reaches the other tools. The exclusion (single-brand accounts need not call it) is implied by the 'more than one brand' qualifier rather than spelled out, and the alternatives are referenced generically rather than named.

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