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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint false, so the description only needs to add contextual behavior. It adds value by detailing exactly what properties are returned and by requiring a specific set of identifiers, giving the agent a richer behavioral picture beyond the annotation flags. No contradictions exist.

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 opens with a concise action statement and then provides a structured enumeration of returned fields, which is useful for an agent deciding whether this tool fits. The field list is lengthy but justified for a 'details' tool; the final sentence about required inputs is somewhat redundant with the schema but still serves as a quick confirmation. Overall, it is well-organized and free of filler.

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?

The description fully covers what the tool does, what it returns, and what inputs are required. Since an output schema exists, return-value details do not need to be repeated, and the annotations already cover the safety/idempotency profile. For a read-only, single-resource detail tool, the description is complete enough for correct invocation.

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 descriptions fully document the three required parameters (project, zone, name) with 100% coverage, so the schema carries the semantic burden. The description merely restates that these inputs are required without adding additional parameter-level meaning, such as formats, constraints, or relationship between the parameters.

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 ('Get') with a clear resource ('Compute Engine reservation details') and then enumerates the distinct types of data returned, such as name, ID, status, machine type, and sharing settings. This detailed property list distinguishes it from sibling tools like get_reservation_basic_info and list_reservations without requiring the agent to compare schemas.

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 implies this is the tool to use when full reservation details are needed, and the 'Requires project, zone, and reservation name' line signals when it applies. However, it does not explicitly state when to prefer get_reservation_basic_info for a summary or list_reservations for enumeration, so the guidance is more implied than clearly stated.

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