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

Annotations cover the safety profile (idempotentHint=true, destructiveHint=false), and the description adds genuinely new traits: the project transitions to awaiting_secrets, no credentials are ever accepted here or anywhere, and a duplicate variable is refused with the conflicting alias named. This is strong behavioral disclosure beyond the annotations.

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-loaded with the core constraint, then defaults, then the workflow and error rule. Dense but every clause adds meaning; the only slightly redundant line is 'This takes the shape only,' which restates the no-credentials point made later.

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?

No output schema exists, and the description compensates by describing the resulting state (awaiting_secrets) and the refusal condition. It is nearly complete for a 5-parameter mutation, with idempotency_key semantics being the main unexplained element.

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 carries the full burden and does so: offering is enumerated (postgres, redis, mysql, mongodb, rabbitmq), alias is explained as the discriminator with a default of 'db', and variable is mapped to per-offering defaults (DATABASE_URL, REDIS_URL, MONGODB_URI, AMQP_URL). Only idempotency_key and project_id semantics are left unstated.

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 ('Declare a backing service the tenant ALREADY RUNS') and immediately distinguishes it from the provisioning path ('so the platform does not provision one'). An agent can separate this from create_service and detach_external without opening a 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?

Clear context for use: only when the tenant already operates the service, with the natural contrast that the platform would otherwise provision it. It also names the follow-on tool (get_secrets_link form) that the human must use. It never explicitly names create_service as the alternative to pick instead, so it stops short of full when/when-not routing.

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