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

The annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds genuine context the annotations cannot: the scope is 'across the whole window' and rows are annotated with an evidence-floor verdict. It omits ordering, whether the roster is exhaustive, and failure behavior (the schema, not the description, carries release_unavailable).

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 that opens with the action and then enumerates returned fields, with essentially no filler. It is somewhat run-on — five distinct return attributes chained with commas — which costs a point against a crisper list form.

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?

With no output schema, the description carries the full burden of describing return values, and it does so thoroughly (model, runs, days, evidence-floor pass/fail, top cited source). Annotations cover the safety profile and the schema covers the one parameter. Only ordering and result-size behavior are left unstated.

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 coverage is 100% and the sole 'release' parameter is fully documented in the schema, including the release_unavailable consequence for non-current releases. The description adds nothing about the parameter, so the baseline 3 applies; it neither compensates nor detracts.

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 ('List') and resource ('each answer engine') and enumerates exactly what each row contains: model, observed runs and days, evidence-floor status, and most-cited source. This is far more than a restatement of the name. It stops short of 5 because it never distinguishes itself from the singular sibling mri_get_engine, leaving the agent to infer that this is the enumerate-all variant.

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 explicit when-to-use or when-not-to-use statement, and no mention of the obvious alternative mri_get_engine for a single engine or mri_list_categories for the category axis. The only implied guidance is that listing 'each' engine means an unfiltered enumeration, which the agent must derive on its own.

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