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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is fully covered structurally. The description adds nothing beyond that—no note on what happens when the ID does not exist, no permission context, no mention of the fields/format output knobs. A terse lookup tool needs little, but zero added context is still zero.

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?

One short sentence with zero filler and the key lookup parameter front-loaded. It is genuinely concise rather than merely under-specified, though the terseness leaves no room for routing or behavioral content.

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 low complexity, has an output schema, 100% schema coverage, and rich annotations, so most structured information is already available to the agent. What remains missing is the routing signal against near-neighbor read tools and any hint about failure behavior for an unknown ID.

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%: userId, fields, and format are all documented in the schema, including enum meanings for 'essential'/'all' and 'json'/'markdown'. The description's 'by ID' merely restates the required userId parameter and adds no syntax or format 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 uses a specific verb and resource ('Retrieve a user by ID'), which is unambiguous about the operation and the lookup key. It does not, however, differentiate itself from the many sibling read tools such as glpi_list_users, glpi_search_user_by_email, or glpi_get_full_session, so an agent must infer the distinction from the name alone.

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_list_users (bulk retrieval) or glpi_search_user_by_email (lookup by email instead of ID). The description offers no conditions, prerequisites, or alternatives, leaving selection entirely to inference.

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