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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the write/overwrite profile is covered structurally. The description nonetheless adds real value beyond them: it spells out that "create or overwrite" is the behavior and that the stored secret is never echoed back, only a confirmation message — a meaningful disclosure for a credential write.

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?

Three tight sentences, zero redundancy, with the action and its overwrite semantics front-loaded before the permission gate and the return-value caveat. Every sentence earns its place.

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 three-parameter credential mutation with no output schema, the definition covers the essentials: what is stored, who may store it, which fields are required, and what comes back (a confirmation, not the secret). The only gap is that it does not say which read/list tool surfaces the stored credential state afterward.

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% and the required/optional split matches the schema's required array exactly, so the description repeats structured data rather than adding to it. The "omit to keep the default" note for apiUrl is already in the schema's own property description.

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 with its exact semantics ("Store (create or overwrite)") plus the resource ("the authenticated customer's Datadog monitoring credentials"). The Datadog naming cleanly distinguishes it from the sibling set_investigation_cloudwatch_credentials without opening either 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?

Gives a concrete precondition — ADMIN only — plus which parameters are mandatory, so an agent knows whether it is allowed to call it. It does not, however, point at alternatives (e.g. the CloudWatch credential setter or list_investigation_agent_context_credentials for reading back state), so the routing guidance is incomplete.

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