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

readOnlyHint=true already tells the agent this is a safe read, and the description usefully supplements that by disclosing the return payload's breadth (evidence items, references, custom attributes, skills) — valuable given there is no output schema. It does not cover error behavior for an unknown id, but the annotation carries the safety profile.

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 tight sentences with the resource and its payload front-loaded, no filler. The trailing "GET /v1/credentials/{id}" endpoint notation is mildly redundant for an MCP caller but costs little.

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 one-parameter read-only tool with no output schema, the field enumeration effectively stands in for a return-value description, and the id semantics match the schema. Nothing an agent needs to invoke it correctly is missing.

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 coverage is 100% and the parameter already documents "numeric id or custom credential id (license_id)"; the description restates the same dual-id semantics almost verbatim. Baseline 3 is appropriate since the schema does the heavy lifting and the description adds no format or lookup nuance.

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 names the resource concretely ("One credential in full") and enumerates exactly which fields come back, so an agent knows this is a single-record retrieval rather than a search. It never explicitly names the sibling it is distinct from (accredible_search_credentials), so sibling differentiation is left to inference.

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 "One credential in full" — a single-record lookup versus the list/search siblings — but there is no explicit when-to-use or when-not-to-use statement, and no mention that a known id is required to call it.

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