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

Annotations already declare destructiveHint=true, idempotentHint=true, openWorldHint=true and readOnlyHint=false, so the safety profile is covered structurally. The description adds nothing beyond that — it doesn't say what fields get overwritten, whether omitted fields are preserved, or whether permissions are required, which is the kind of context a mutation tool benefits from.

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?

A single front-loaded sentence with no filler or repetition, which is appropriately sized for a simple two-parameter update. It is efficient, though the terseness edges toward under-specification rather than optimal economy.

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 tool is a mutation with a nested input object, but an output schema and full annotations are present, so return values and safety traits needn't be restated. What remains missing is semantic context about the update itself (partial vs full replacement of fields, permission requirements), leaving the definition only minimally complete.

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%: reservationId is documented as the item ID and the input object already enumerates the updatable fields (begin, end, comment, users_id). The description adds no format, validation, or nesting detail beyond the schema, so the baseline 3 applies.

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 states a specific verb (Update) and resource (reservation) plus the lookup key (by ID), so the agent knows exactly what operation this performs. It does not, however, differentiate itself from the other reservation tools (glpi_create_reservation, glpi_get_reservation, glpi_list_reservations), which the name alone has to disambiguate.

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?

There is no guidance on when to use this tool versus glpi_create_reservation or glpi_get_reservation, nor any stated preconditions (e.g., the reservation must already exist, required permissions). The single phrase 'existing reservation' implies a precondition but does not state one explicitly.

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