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

Annotations already declare destructiveHint=true and idempotentHint=true, so the destructive nature is disclosed. The description adds valuable context beyond annotations: deleting a contact does not block the number, and opt-out requires add_to_blacklist. This clarifies the tool's real-world effect without contradicting 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 description is concise, with two short sentences. It front-loads the primary action and immediately follows with the key constraint and alternative. Every sentence adds value.

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 tool with one parameter, a high-coverage schema, an output schema, and annotations covering idempotency and destructiveness, the description is complete. It tells the agent what the tool does, what it does not do, and which alternative to use when needed.

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?

The input schema already covers the single parameter 'id' with 100% coverage, describing it as 'Id kontaktu ct_…'. The description adds no additional parameter meaning, which is acceptable since the schema carries the semantic load. Baseline 3 is 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 clearly states the action: 'Delete contact' / 'Remove a contact from the address book.' It specifies the exact resource (a contact in the address book) and distinguishes itself from the sibling add_to_blacklist by noting what it does NOT do.

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 explicitly tells the agent when not to use this tool: if the goal is opt-out or blocking, use add_to_blacklist instead. It also implies delete_contact is for removal from the address book, not for blocking a number, which gives clear decision guidance.

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