credentials

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

With no annotations, the description carries the full behavioral burden, and it delivers the single most important property: this exposes credential metadata only, never secret values. That implicitly signals a safe read operation and prevents an agent from expecting a key it can use directly. It omits return ordering, empty-vault behavior, and error conditions, so it is not exhaustive, but the security-critical disclosure is present.

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 sentences, both earning their place: the first defines the payload and its boundary, the second gives the action instruction and the safety rule. The non-obvious constraint ('never values') is embedded in the first sentence where an agent will actually read it.

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 parameterless lookup with no output schema, the description tells the agent what comes back (names, services, destinations) and what never does (values), which is the substantive part of the return contract. It leaves the concrete response shape unspecified, but the essential semantics are covered.

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 no parameters, so there is nothing to disambiguate and the schema (trivially 100% covered) is empty. The baseline for a zero-parameter tool is 4, and nothing in the description is misleading about inputs.

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 defines the resource precisely: the user's API keys held by Commons, returning names, services, and allowed destinations but never values. This is clear enough to distinguish it from sibling tools, and it explicitly names use_credential as the companion action. It stops short of a clean action verb (it reads as a noun phrase, not 'list credentials'), which is the only thing keeping it from a 5.

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?

It gives an explicit next step ('Use one with use_credential') and a hard rule ('never ask the user to paste a key'), which tells the agent both why to call this tool and what to do with the result. It does not spell out when it is unnecessary to call it, but for a zero-argument lookup the routing guidance is strong.

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