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

Annotations already provide readOnlyHint=false, destructiveHint=true, and idempotentHint=true, so the description's 'Delete' is consistent. It adds minimal extra behavioral context beyond the annotations, mainly the scheduled/sent scope, which is mostly purpose rather than side effects.

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 very short and the meaningful sentence is front-loaded. However, it repeats the tool title 'Delete Message' as a heading, which is redundant given the title field is already present.

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 single-parameter delete operation with an output schema and annotations covering the destructive and idempotent behavior, the description provides all necessary context. The scope of what can be deleted is clearly stated, and no return-value explanation is needed because an output schema exists.

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% and the single id parameter is already documented as 'Unique numeric identifier for this message.' The description adds no further parameter-level meaning, so the baseline of 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 uses a specific verb ('Delete') and resource ('scheduled or sent outreach message') and adds scope ('for the authenticated project'). This clearly distinguishes it from listing, updating, or canceling tools, even without naming a sibling.

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 clear context by specifying the message states this tool applies to: scheduled or sent outreach messages. It does not explicitly exclude alternatives like cancelCustomerUnsentMessages, so it stops short of full when-not guidance.

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