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

The 'MUTATING' prefix and the endpoint reinforce the mutation, but annotations already declare destructiveHint=true, so the safety profile is covered structurally. The description does not disclose meaningful traits beyond that – e.g., that setting instances to 0 effectively stops the service, whether existing instances are drained gracefully, or whether the change is reversible.

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?

Two short sentences, front-loaded with the mutation warning so the risk is the first thing the agent reads. Nothing extraneous; every clause carries signal.

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 3-required-param mutation with full schema coverage and no output schema, the definition covers purpose and mutation adequately. It misses operationally relevant context such as the consequence of scaling to 0 and any disruption, which would matter for a destructive infra tool, but the destructiveHint annotation partly compensates.

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 100%, so all three parameters (projectId, serviceId, instances) are already documented in the schema, and the description adds no syntax, format, or semantic detail beyond restating 'instances/replicas'. Baseline 3 applies when the schema does the heavy lifting.

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 ('set') and resource ('number of running instances (replicas) for a service'), clarifying the exact effect. This clearly distinguishes it from siblings like restart_service, pause_service, and resume_service, which the agent can rule out without opening any schema.

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 by the name and purpose – an agent can infer this is for changing replica count – but there is no explicit when-to-use guidance or mention of alternatives such as pause_service (temporary stop) or restart_service. The absence of any condition distinguishing scaling from those siblings is a real gap.

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