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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered, and 'Behavior: read_only' merely restates it. The description does add value beyond annotations by disclosing that workspace_id/user_id are injected from request headers (no caller-supplied scoping) and by giving a multi-record handling rule for the caller.

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 purpose, then cleanly sectioned into Use when / Behavior / Returns / IMPORTANT. The only waste is the six-field Returns list, which duplicates the existing output schema, and the 'Behavior: read_only' line that repeats the annotation.

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 zero-parameter read-only lookup with an output schema, the description covers everything needed to select and call it correctly. The verbose Returns list is redundant given the output schema, and the trailing IMPORTANT multi-record/user-choice instruction reads like generic boilerplate rather than a trait of a fixed transition table, but it does not mislead.

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?

Zero parameters, so the baseline is 4. The description confirms 'No input parameters required,' which matches the empty schema, though it adds nothing beyond that confirmation and the header-injection note.

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: 'Return the full state machine transition table for referrer requests,' and enumerates exactly what each entry contains (source state, target state, actor, event, label). This is unambiguous against siblings like referrer_request_get_current_state (single state) and referrer_request_send_state_change_event (mutation).

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?

Explicit when-to-use: 'Call to understand all valid transitions before firing SendStateChangeEvent on a referrer request,' naming the downstream sibling tool that consumes this data. It also notes no input parameters are required. It stops short of stating when *not* to call it or how it differs from get_current_state, so it's clear context without exclusions.

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