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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds non-obvious behavior beyond them: it returns the credential default plus identities, and explicitly asserts the call 'never changes the default' — a side-effect clarification an agent genuinely needs.

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 tight sentences, each doing distinct work: scope, return shape, and downstream usage. The most important constraint ('this never changes the default') is placed last where it lands, and nothing is padded.

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?

An output schema exists, so return-value structure need not be explained, and the description still usefully names what comes back (default + identities). For a zero-required-param list tool with full schema coverage, the only minor omission is pagination semantics, which the schema handles.

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%, so limit, offset, reason and account_id are all documented in the schema, and account_id's description already says 'for this call only'. The description's account_id sentence is essentially a restatement of that, adding no syntax or constraint detail beyond the structured data — 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?

States a specific verb+resource ('List accounts') and narrows the scope to those 'explicitly granted to this connection', which is meaningful in a multi-account credential model. It does not explicitly contrast itself with the close sibling account_get, so an agent must infer the plural/singular distinction from the names 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?

It gives forward-looking guidance ('Pass account_id on later tools to select one'), which implies this tool is the discovery step in an account-selection workflow. However, it never states when to use this versus account_get or account_limits, and offers no exclusions or preconditions.

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