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

Annotations only indicate not read-only and not destructive; the description goes beyond that by disclosing that this operation establishes a login session and is a prerequisite for other calls. It does not mention session expiry, repeated-login behavior, or error conditions, but the essential behavioral trait is conveyed.

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 short sentences, with the critical sequencing instruction front-loaded before the action statement. No filler or repetition of schema details.

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 simple login tool with one required parameter and 100% schema coverage, the description provides the essential prerequisite context and auth method. It would benefit from noting how to verify login success via nps_edi__auth__session__status, and there is no output schema, but the core call path is clear.

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%, so the parameter semantics are already fully documented, including the optional/auto-resolved account_link_id and the required business_management_no format. The tool description itself adds no parameter information, making the baseline 3 appropriate.

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 states a specific action ('Login to NPS EDI via NPKI certificate') and adds a sequencing cue ('Call this FIRST'), which distinguishes it from the many sibling login/session tools by identifying both the provider and the auth method. The title and tool name reinforce the resource.

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 tells the agent exactly when to invoke this tool ('FIRST before any other tool for this provider'), which is strong usage context. It does not document exclusions such as 'skip if a session already exists' or direct the agent to the nps_edi__auth__session__status sibling, so it falls short of fully explicit when-not guidance.

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