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

Annotations only declare the generic mutation profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false); the description adds real substance beyond that: the first 'reached' mark locks the bet, a reached email increments the daily drafts counter, and the operation is free. What is not disclosed is idempotency and overwrite behavior when a person is marked twice or a status is changed.

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?

Front-loaded with the core action, and the parenthetical glosses on 'reached' and 'skipped' earn their space by disambiguating the enum values. The wording is dense and nestles several clauses in one sentence, and the trailing 'Free.' is clipped to the point of being cryptic.

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 two-parameter mutation with annotations and no output schema, the description covers the outcome vocabulary, the state-locking side effect, and the cost, which is close to what an agent needs. The remaining gap is return/feedback behavior and what happens on repeat marking.

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 50%, and the description does add meaning to the undocumented parts: it defines what 'reached' and 'skipped' actually mean and gives example reasons for the nested 'why' field ('closed inbox, no address, the founder passed'). It does not explain the 'id' selection semantics beyond what the schema already says, so it partially but not fully compensates.

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?

States a specific verb and resource: it records which of today's Bullseye Test people were reached versus skipped, and defines each outcome inline ('the founder sent it, or an email's draft is saved'). An agent can tell this is the outcome-logging step of the Bullseye flow, though it never names a sibling such as bullseye_change or bullseye_read to sharpen the boundary.

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?

Usage is implied rather than stated: the mention of 'today's Bullseye Test' and 'the first reached locks the bet' suggests this is called after outreach happens, but there is no explicit 'use this when X, not when Y' routing against the several other bullseye_* siblings. No prerequisites or exclusions are given.

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