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

The description states 'Read-only and non-destructive; not separately rate-limited,' which matches annotations (readOnlyHint, destructiveHint=false) and adds the rate-limit detail beyond them. It also clarifies the return includes source_id and schema components. No contradiction with 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?

The description is relatively concise but repeats the list of schema components twice (once at the start, once at the end), adding redundancy. The 'Advanced tool' preface adds little value. Front-loading is decent, but trimming repetition would improve clarity.

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 simple one-parameter read-only tool, the description covers the prerequisite (list_sources), the output components, and safety characteristics. No output schema exists, but the listed return fields give a good picture. It omits potential error handling or size limits, but that's minor for this scope.

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 schema description for source_id is already clear ('Source ID from list_sources'), and the description reinforces this by telling the agent to use list_sources. With 100% schema coverage, the added guidance on how to obtain the ID is helpful but not strictly necessary.

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 clearly states the tool gets the full schema for a registered source, listing specific components (column types, cardinality, fill rates, formula relationships, join keys). It distinguishes the resource type (registered source) but does not explicitly contrast with sibling get_data_schema, which could cause confusion. Still, the purpose is concrete and actionable.

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 instructs to use list_sources to find source ids, which is a useful prerequisite. However, it does not mention when to avoid this tool or point to alternatives like get_data_schema, leaving some ambiguity for an agent deciding between schema tools.

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