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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses the prerequisite (creator_key), the side effect on viewers (all see it as confirmed with add-to-calendar buttons), and the return value (calendar links). It does not mention whether locking is reversible or error conditions, but it covers the key behavioral aspects for a locking action.

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 three sentences long, front-loads the primary purpose, and every sentence contributes distinct information: prerequisite, two modes, outcome, and return value. No filler or redundant phrasing.

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 the absence of an output schema, the description wisely states the return value (calendar links). It provides enough context for the agent to understand what the tool does and when to invoke it. Minor gaps include lack of error handling or idempotency details, but the essential use-case is well covered.

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 67% (4 of 6 properties have descriptions), and the description compensates by explaining the relationship between parameters (use_best vs day/start) and the origin of creator_key. It adds semantic meaning beyond the raw schema, helping the agent decide which parameters to provide based on the scenario.

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 and resource ('Lock the final time on a plan'), making the tool's purpose immediately clear. It distinguishes itself from sibling tools by focusing on finalization/confirmation rather than listing, creating, or planning, and it clarifies the two modes of operation (use_best vs explicit day/start).

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 clear context: it requires the creator_key from whenna_create_plan and explains how to choose between automatic best-time locking or explicit scheduling. While it doesn't explicitly state when not to use this tool or compare to alternatives like whenna_best_times, the context strongly implies this is the final confirmation step after selecting a time.

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