pg_summary

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

Goes well beyond the readOnlyHint annotation to disclose the truncation contract: unhealthyCount is the true total while the unhealthy list is capped at limit and flagged truncated:true, with explicit advice to re-run at a higher limit. This is exactly the non-obvious behavior an agent needs to avoid misreading a partial result as complete.

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 one-line purpose, then adds guidance in descending order of importance. The truncation warning and Args block are justified, though the description runs longer than strictly required for a two-parameter read tool.

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 read-only tool with no output schema and two params, the description covers what is returned, the truncation edge case, and both arguments. Nothing an agent needs to call it correctly is missing.

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%, so the description must carry the params, and it does: target (Ceph target name from config, omit for default) and limit (max unhealthy rows, default 200). Both are explained beyond their bare names, though target's expected format is only loosely characterized.

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+resource with precise scope: a PG state histogram plus every PG not active+clean. It is clear enough that an agent understands exactly what comes back, but it never differentiates itself from the closest sibling (pg_dump_stuck), which an agent could plausibly reach for on the same question.

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?

Gives concrete usage context for when to invoke ('are my PGs healthy?') and what it answers. It stops short of naming exclusions or pointing to pg_dump_stuck for the stuck-PG case, so it is clear context without alternatives.

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