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

The annotations already mark this as a destructive write, and the description adds important behavior beyond them: partial update semantics, required pre-existence, error on wrong id, overwriting current values, and a recommended dry-run validation step. This is exactly the kind of mutation context an agent needs before invoking the tool.

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 four short sentences, front-loads the write operation, and every sentence contributes useful information about existence requirements, patch behavior, overwrite behavior, or dry_run. There is no wasted text.

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 15-parameter destructive update with full schema coverage and no output schema, the description covers the essential invocation context: existing record required, partial update, destructive overwrite, and dry-run validation. It could add a note about what happens on success or how to verify the result, but nothing critical for correct invocation 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 description coverage is 100%, so the baseline is 3, but the description adds meaningful semantics about how optional parameters behave: only the fields passed are changed. It also reinforces dry_run as a validation-only mode, which helps the agent reason about the parameter set as a whole.

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 verb and resource: change fields of an existing address-book entry. It also distinguishes this from create operations by explicitly saying a wrong id is an error and nothing is created, so an agent can tell it apart from abraflexi_create_contact without inspecting either 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?

It gives clear usage context: the entry must already exist, only passed fields are changed, and dry_run should be used first to check. It does not explicitly name alternatives such as using abraflexi_get_contact to obtain the id or abraflexi_create_contact when the entry is missing, so it falls short of full when/when-not/alternative guidance.

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