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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description's 'deterministic' largely restates idempotentHint, while 'source-labelled' is a mild hint about output shape; it adds little behavioral context beyond the annotations.

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 verb, resource and scope and no filler. Nothing could be removed without losing information, and the key constraint (one topic) comes last in a natural reading order.

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 an output schema covering return values and annotations covering the safety profile, plus an enum-constrained two-parameter input, the description is nearly sufficient for correct invocation. The remaining gap is that it neither explains the source_id enum values nor distinguishes itself from overlapping siblings like faith_service_evidence.

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%, but both parameters are enums that self-document their valid values. The description adds only 'supported topic' for topic and implies a source labelling for source_id, but never clarifies what 'bsb' vs 'web' means or what the topics represent, leaving the cryptic source_id identifier under-explained.

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 ('Return') and resource ('source-labelled evidence guide') scoped to 'one supported topic', which an agent can distinguish from passage-context or cross-reference siblings. However, it never names an alternative, and 'evidence guide' overlaps semantically with the sibling faith_service_evidence, so differentiation is only partial.

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?

There is no when-to-use guidance, no when-not-to-use, and no mention of any alternative tool among the ten siblings. The phrase 'one supported topic' implies a constrained input but says nothing about when this guide is the right choice over a lookup or search.

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