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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description goes beyond them by disclosing data minimization (notes, permissions, attachments, personal/payroll fields are omitted) and the customer API access requirement, which are real behavioral facts an agent could not infer from structured fields.

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?

Four short, front-loaded sentences covering purpose, return scope, exclusions and access constraint; nothing is redundant. It stops just short of a 5 because the phrasings are terse fragments rather than a tightly unified statement.

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 read tool with no output schema, the description gives the caller what matters: what is returned at a coarse level, what is deliberately withheld, and that customer API access is required. Return structure specifics are the only gap, and no output schema exists to cover them.

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?

Only one parameter with 0% schema description coverage, so the description must carry meaning. "its known id" clarifies that the argument is an existing opportunity identifier rather than a name or filter, but adds no format, range, or lookup guidance beyond that, so compensation is partial.

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 (Read) and resource (one opportunity) plus the selection mechanism (its known id). The sibling tools all target different resources (contact, project, schedule), so no disambiguation is needed, though the description never explicitly contrasts itself with any of them.

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?

"using its known id" implies the precondition that the caller already has an opportunity id, which mildly rules out search-style usage. However, it never states when to prefer this over a listing/search tool or what to do when the id is unknown, leaving usage to inference.

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