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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions 'Requires write_mode', which hints at permission requirements, but doesn't describe other critical behaviors such as whether the update is idempotent, what happens on failure, if changes are reversible, or any rate limits. For a mutation tool with zero annotation coverage, this is a significant gap in transparency.

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 extremely concise with only two sentences, front-loading the core purpose ('Update an existing credential') and adding a critical prerequisite ('Requires write_mode'). There is no wasted text, and every word serves a functional purpose, making it efficient and easy to parse.

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?

Given that there is an output schema (which reduces the need to describe return values), no annotations, and low schema coverage, the description is minimally adequate. It covers the basic purpose and a prerequisite but lacks details on parameters, behavioral traits, and usage context, leaving gaps that could hinder effective tool invocation by an AI agent.

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 0%, meaning parameters are undocumented in the schema. The description adds no information about the parameters (credential_id, name, data), their meanings, formats, or constraints. It doesn't compensate for the lack of schema documentation, leaving the agent with insufficient guidance on how to use the inputs effectively.

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 clearly states the action ('Update') and resource ('an existing credential'), which is specific and unambiguous. It distinguishes from sibling tools like 'create_credential' and 'delete_credential' by focusing on modification rather than creation or deletion. However, it doesn't specify what aspects of the credential can be updated (e.g., name, data), leaving some ambiguity compared to the 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?

The description provides some usage guidance by mentioning 'Requires write_mode', which implies a prerequisite condition for use. However, it doesn't explicitly state when to use this tool versus alternatives like 'create_credential' for new credentials or 'delete_credential' for removal, nor does it clarify if there are specific scenarios where this tool is preferred over others.

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