replication_lag_rca

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely useful behavior beyond that: omitting 'status' triggers a live pull and the result is 'flavor-branched', which an agent needs to know before calling. No auth or rate-limit detail, but the live-vs-offline distinction is the important trait here.

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 purpose, then the mode selection, then an Args block. The mode explanation is repeated between the second sentence and the 'status:' arg line, which is mild redundancy, but the layout is otherwise tight and scannable.

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 2-param, no-required, read-only tool with no output schema, the description covers what it does, the two invocation modes, and starts to describe the return ('cause + action'). It could say more about the shape of the diagnosis output, but nothing critical for correct invocation 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 description coverage is 0%, so the description must carry the burden, and it does: it explains that 'status' is an injected replica status record (omitted = pulled live) and 'target' comes from config with a default when omitted. Both parameters are meaningfully documented.

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: 'Map replica thread state / lag / error fields to cause + action', with a [READ] tag. This clearly differentiates it as a diagnostic RCA mapper rather than a raw status reader, though it does not explicitly name the sibling (replica_status) it complements.

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?

Explains the two operating modes ('pass status' for offline analysis vs 'omit' for live pull) and points to replica_status as the source of a status record. However, it gives no guidance on when to choose this tool over the other RCA siblings (lock_wait_rca, slow_query_rca) in the same family.

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