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

With no annotations provided, the description carries the full burden and does substantial work: it discloses that the operation is a mutation limited to one field, that bank details are immutable at the partner, and that the operation is free of charge. The 'Free.' note adds a cost-related behavioral trait an agent would not otherwise know, though it stops short of describing the response shape or immediacy of the change.

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 description is compact and front-loaded: a one-line headline, a clarifying restatement, the key constraint, and a one-word cost disclosure. Every sentence earns its place and nothing is wasted.

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 3-parameter tool with no output schema and no nested objects, the description covers purpose, scope, the only editable field, the alternative procedure, and cost, while the schema documents all parameters at 100%. The only minor gaps are not naming the sibling delete/create tools explicitly and not stating what the response contains.

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 schema already fully documents nickname (including the empty-string-clears behavior), destinationId, and the conditional auth_token. The description's 'Sets or clears' reinforces the nickname semantics but adds only marginal meaning beyond the schema, which is the baseline-3 situation.

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 opens with a specific verb+resource pair ('Rename a destination') and immediately clarifies the exact operation ('Sets or clears a destination's nickname'). It differentiates from siblings by stating that the nickname is the only editable field, which is a meaningful distinction from delete/create banking tools.

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?

The description gives explicit when-to-use guidance (renaming/setting/clearing a nickname) and explicit when-not-to-use guidance ('anything else wrong means deleting the recipient and creating a new one'). This clearly routes the agent to the delete+create alternative instead of attempting edits this tool cannot perform.

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