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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=false): it discloses that secrets are never accepted as MCP inputs, that each call consumes one token (호출마다 토큰 1소진), and gives detailed idempotency-key lifecycle semantics. These are substantive behavioral facts the agent could not infer from the annotations.

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 critical ordering instruction is front-loaded in the first sentence, and most content earns its place. Minor deduction for some awkward phrasing ('anonymous taste calls', repeated idempotency caveats) that slightly muddies an otherwise tight description.

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 session-login with two optional params and no output schema, the description covers auth behavior, call ordering, idempotency recovery, token cost, and field disambiguation. 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%, so the schema already documents both parameters. The description still adds real value by explaining request_idempotency_key reuse rules and explicitly distinguishing it from a provider-specific idempotency_key, though account_link_id handling is left entirely to the 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 specific verb+resource ('Create a Hana Bank fast-account inquiry session from an existing account link') and adds an ordering constraint ('Call this FIRST before any other tool for this provider'). An agent can distinguish this session-login from the sibling accounts__list and transaction_history__search tools without opening any 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?

Explicitly tells the agent to call it first before other provider tools, which is the key usage rule for a session bootstrap. Idempotency reuse vs. new-execution conditions are also spelled out. It lacks an explicit 'when not to use' clause, but as the only Hana session tool there is no alternative to redirect to.

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