Index health

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

Goes well beyond the readOnly/idempotent annotations to disclose that unused and missing-index data comes from server DMVs, that these reset on SQL Server restart, that without VIEW SERVER STATE the values come back null, and that 'visibility.unavailable' explains why while duplicates are still reported. This is exactly the kind of operational caveat an agent needs to interpret results correctly.

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 tightly packed sentences: purpose/outputs first, routing guidance second, data caveats third. No filler, and the key scoping information is front-loaded. It is dense but every clause 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?

With no output schema, the description carries the return-value burden and does so by naming the three result categories and explaining the null/'visibility.unavailable' failure mode. Combined with the sibling routing and permission caveat, an agent has everything needed to call and interpret this tool.

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 100%, so both parameters (schema filter, database) are already documented in the input schema, including the empty-string default and an example. The description reinforces the by-schema scoping but adds no syntax or format detail beyond the schema, so baseline 3 applies.

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 (Reports) and resource (index health) and enumerates the three output categories: duplicate index candidates, unused indexes, and missing-index suggestions. It also names the sibling it is not (get_table_schema for a single table), so an agent can distinguish it 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?

Explicitly says when to use it ('when reviewing indexing or slow queries') and routes the agent to an alternative for a narrower case ('for one table's indexes use get_table_schema'). Both the selection condition and the exclusion are stated, leaving nothing to inference.

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