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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false. The description adds useful behavioral context beyond those flags: the exact error codes when a service is capped or disabled, the response shape, and the fact that an API key is required. It does not add rate limits or detailed side-effect warnings, but the annotation coverage lowers the burden.

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?

Every sentence earns its place: purpose, read-vs-change usage, sibling distinction, output shape, error conditions, and authentication. The information is dense but not padded, and the core operation is stated first.

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 description is complete enough for a 3-parameter tool with no output schema: it explains the return JSON, error semantics for capped/disabled states, authentication needs, and the read/change distinction. Nothing required to decide whether or how to call the tool is missing.

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 the baseline is 3, but the description adds real semantic value: it enumerates the valid service keys, connects 'no arguments' to read mode, connects enabled/caps to write mode, and clarifies the account-wide scope. Since the schema has no enums, this extra detail is meaningful.

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 names a specific verb and resource, 'Read or change the account-wide service settings,' and lists the exact gateway services involved (rpc, data, gas, tx_status, ens, prices, contracts, utils). It also explicitly distinguishes itself from the per-key sibling by saying 'Not for one key's budget or services (use configure_key).'

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?

It gives explicit when-to-use guidance: 'Use it with no arguments to read; pass enabled and/or caps to change.' It also names the alternative tool for a different scope, configure_key, and provides functional consequences such as error -32014 for capped services and -32012 for disabled ones.

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