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

Annotations already declare readOnlyHint=true, so the safety profile is partly covered, but the description adds genuinely useful context beyond them: the endpoint path, the hard rejection of mutations at runtime, and that variables are optional. It stops short of other operational traits such as auth requirements, pagination, or rate limits, so it is strong but not exhaustive.

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?

Three sentences, front-loaded with the 'Escape hatch' framing so the tool's role is immediately clear, and every sentence carries routing or constraint information. The uppercase emphasis on QUERY/REJECTED is slightly shouty but reinforces the single most important rule of the tool.

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 an arbitrary-query passthrough with no output schema and only two well-documented parameters, the description covers role, endpoint, constraint, and alternatives. Return shape is implicitly whatever the query selects, which is reasonable, though a note that the caller owns the response shape would make it fully 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%, so both parameters are already documented in the schema ('must be a query, not a mutation' and the variables object). The description echoes this ('with optional variables') without adding syntax, formatting, or example-level detail, so the baseline of 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?

States a specific verb and resource ('run an arbitrary Memberful GraphQL QUERY') plus the scope constraint (read-only, against your account's /api/graphql endpoint). It explicitly contrasts itself with the curated read tools and with memberful_graphql, so an agent can pick it apart from siblings without opening a schema.

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?

Gives both the when ('fields not covered by the curated read tools, e.g. member-state filters beyond active') and the when-not ('Mutations are REJECTED — use the dedicated write tools or memberful_graphql for those'), naming alternatives explicitly. This is exactly the routing information an agent needs.

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