replica_status

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

Annotations declare readOnlyHint=true, and the description's '[READ]' tag is consistent with that. It adds real behavioral context beyond the annotation: flavor-branched queries (MySQL 8.x vs MariaDB), normalization of results, and the empty-result case on a primary. That is meaningful disclosure for a read tool.

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 in the first sentence and uses short paragraphs, with no filler. The args block is slightly redundant with the schema but remains compact.

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 and a 1-param signature, the definition covers the essentials: what it returns, when it is empty, and how flavor differences are handled. It stops short of describing the shape of the replica-status rows, but the content is adequate for correct invocation.

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 carries the burden, and it does document the single parameter: 'target: Target name from config; omit for the default.' This explains the naming convention and the default behavior, which the bare schema does not.

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 and resource — '[READ] Replica thread state and lag' — and immediately names the underlying SQL (SHOW REPLICA/SLAVE STATUS). An agent knows exactly what data this returns, though it does not explicitly contrast itself with the sibling replication_lag_rca.

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?

Provides a useful applicability condition ('Empty on a primary/standalone server'), which tells the agent when NOT to expect results. However, it never states when to prefer this over replication_lag_rca or binlog_status, leaving the choice among replication siblings to inference.

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