count_signals

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

With no annotations, the description carries the full burden, and it usefully discloses that the tool is deprecated and internally uses the deprecated sdv.databroker.v1.ListMetadata RPC. It also clarifies the count-only behavioral scope. It does not discuss error behavior for invalid branches or empty results, but for a simple read-only count tool the key operational caveat is surfaced.

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?

The description is front-loaded with the core purpose, followed by the use case, deprecation warning, and parameter details. The deprecation is mentioned twice (in the bracket and the note), a small redundancy, but every other sentence earns its place.

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?

Given that an output schema exists and the tool is a simple count operation, the description covers purpose, parameters, and deprecation adequately. It omits exact empty-result or error behavior, but those are low-stakes for this tool and the structured data partially compensates.

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 input schema provides no descriptions, so the description must compensate, and it does by explaining branch as a VSS path with examples and query as an optional substring. It adds meaning beyond the raw schema fields, though it could be more precise about matching semantics and default handling.

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 plainly states that the tool counts signals under a VSS branch, using a specific verb and resource. It also contrasts itself with list_signals by saying it 'returns only the count', so an agent can distinguish it from the most similar sibling without opening schemas.

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 explicitly indicates this tool is useful for 'quickly checking how many signals exist without fetching details', which tells the agent when to choose it over list_signals. It does not enumerate all exclusion cases, but the count-only purpose is a clear selection signal.

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