unused_indexes

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

Annotations already declare readOnlyHint=true, and the description adds genuinely useful behavior beyond that: the source table and the fact that counters reset on server restart, which materially affects how results should be interpreted. It stops short of describing return format or scale of output.

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?

Front-loads the [READ] tag and the core result in the first clause, then adds only the caveat and the one argument note. No filler sentences.

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 one-optional-parameter read tool with no output schema, the description covers purpose, data source, interpretation caveat, and the argument. Only a note on output shape or expected result volume is absent, which is minor here.

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 coverage is 0% and the single parameter has no description in the schema, so the description carries the burden. It explains that 'target' is a name from config and that omitting it selects the default, which is exactly the missing semantics.

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 resource and filter: 'Secondary indexes with zero I/O events since restart (drop candidates)', plus the exact underlying table. This clearly separates it from siblings like redundant_indexes and index_stats, which an agent can distinguish without opening any schema.

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?

Identifies the intent (finding drop candidates) and gives a real usage caveat: counters reset on restart, so confirm over a full business cycle. It doesn't explicitly name alternatives (e.g., redundant_indexes) or state when not to use it, so it falls short of a 5.

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