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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond that by disclosing return content — each adapter plus the config fields it accepts — which is the key behavioral fact for planning a follow-up call. It doesn't mention pagination or output shape, but the list is scoped to a single deployment, so that omission is minor.

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 core content is front-loaded in one dense sentence, followed by a short prerequisite directive. The trailing 'Served by NicheDB (https://nichedb.dev/docs/mcp).' is boilerplate that adds little, keeping this just short of a 5.

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 no parameters, the description carries the burden of describing the result, and it does so in brief ('with the config fields each takes'). Combined with annotations covering safety and idempotency, an agent has enough to call it and use the result correctly; only the exact return shape is left implicit.

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?

The tool takes zero parameters, so the baseline of 4 applies. Nothing in the description conflicts with the empty schema.

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 concrete resource and scope: 'Every adapter this deployment can run, with the config fields each takes.' An agent can immediately tell this is a deployment-scoped adapter inventory rather than a data query. It doesn't explicitly distinguish itself from the many sibling list_* tools, but the resource noun ('adapters') is specific enough to be unambiguous.

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?

Gives a clear triggering condition: 'Use before add_source,' which tells the agent this is a prerequisite lookup rather than a terminal action. There is no explicit when-not or named alternative, but the sequencing guidance is concrete and actionable.

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