Get service graphs

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

Beyond readOnlyHint/openWorldHint=false, the description discloses genuinely new behavioral facts: invalid metric/period/field produces a 422 with invalidParameter and allowedValues, fc_* metrics are Firecracker-only, and services:read is required with an API key. It stops short of describing the shape or volume of the returned series.

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?

Four tight sentences with the purpose front-loaded and no filler. 'pick a metric and a period' mildly restates the three required parameters, which is the only redundancy.

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, the description carries the full burden of describing returns and only says 'one performance graph series' — the agent learns nothing about timestamps, point counts, or units. Authorization, error semantics, and metric availability are well covered, but the return contract is a real gap.

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 100% and the schema itself enumerates every allowed value, so the baseline is 3. The description still contributes one cross-parameter constraint not in the schema: fields only narrows the io/net/fc_* metric families, and it flags that invalid values are echoed back via allowedValues.

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 first sentence states a precise verb+resource+scope: 'Get one performance graph series for a service'. The singular 'one ... series' plus 'pick a metric and a period' tells the agent exactly what unit of data comes back, which no sibling (get_service, get_service_history) offers.

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?

Usage is implied rather than stated: metric/period selection and the note that fc_block, fc_net_native and fc_pressure exist only for Firecracker VPS are constraints, not when-to-use guidance. The permission prerequisite (services:read with an API key) is a useful gate, but there is no mention of alternatives or when NOT to call this.

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