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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuine behavioral context beyond them — the page always shows all accounts, there is no single-account filter, and institution_id can narrow to one bank — but does not say anything about how navigation manifests (new view, replaced state) or what happens with an out-of-range month.

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?

Strongly front-loaded: purpose, then routing cues, then alternatives, then constraints. It is on the longer side; the parenthetical URL path and the four example queries are useful but the path is arguably expendable, keeping it just short of fully tight.

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 navigation tool with zero required params, no output schema, and full annotation coverage, nothing an agent needs is missing: purpose, disambiguation from siblings, and the absence of account-level filtering are all stated.

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 schema already documents year/month omission, the grouped vs. institution_id exclusivity, and default-to-all behavior. The description mostly echoes that ('Omit year/month for current balances', 'pass institution_id to narrow to one bank'), adding only marginal nuance about when the bank is known, so 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 (deep link to Account Summary) with the URL path and exactly what the page contains — per-account balances and recent activity as of a chosen month. It explicitly distinguishes itself from navigate_to_net_worth and navigate_to_cashflows, so an agent can route 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 concrete selection triggers with example user phrasings ('how much is in my savings', 'my ANZ balance', 'what were my account balances at the end of March') and names the two alternative tools with the conditions that select them (overall worth vs. money in/out). It also discloses a real constraint up front: no single-account filter exists.

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