describe_db_instance_performance

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

Annotations (readOnlyHint=true) cover the read-only nature. The description adds value by listing example performance metrics (MemCpuUsage, QPSTPS, etc.) that the tool returns. However, it does not disclose other behavioral traits like rate limits or pagination.

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?

The description is concise: one sentence for purpose followed by a clear bullet list of parameters with examples. No unnecessary words, well-structured for quick parsing.

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?

Given the tool has 6 required parameters and no output schema, the description covers purpose and parameters but lacks information about the return format (e.g., whether it returns a list or object). The mention of metrics is helpful but incomplete without output structure.

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 compensate. It provides example values for each parameter (e.g., region_id: cn-hangzhou, perf_keys: array of strings), adding meaning beyond the schema titles. However, format details like date-time format for start_time/end_time are not explicitly specified.

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?

The description clearly states the tool queries performance data from RDS, with a specific verb ('Queries') and resource ('instance'). It distinguishes from siblings like describe_db_instance_attribute by focusing on performance metrics, but does not explicitly contrast.

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?

No guidance on when to use this tool versus alternatives like describe_db_instance_attribute or describe_slow_log_records. The description implies use for performance monitoring but lacks explicit context or exclusions.

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