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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the lower bar applies; the description still adds non-obvious behavior — the view is forward-looking and past actuals are off by default, and the id filters are inverted internally so callers must pass the items they want visible. It stops short of saying what the call actually returns (a URL, a navigation event) or whether it mutates saved UI state when omitted filters are used.

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?

Front-loaded with the destination and view, then triggers, then alternatives, then parameter caveat — a sensible order. It is a dense single paragraph and the filter-inversion sentence partially duplicates what the schema already states, but no sentence is pure filler.

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 zero-required-parameter read-only navigation tool with fully documented schema, the description covers purpose, routing, and the one surprising behavioral trait. The only gap is that the return value (what a 'deep link' navigation produces) is implied rather than stated, which matters slightly since there is no output schema.

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 the baseline is 3; the description earns one extra point by explaining the counterintuitive inversion ('the app inverts them internally — always pass what you want visible'), which is the single most likely parameter mistake. However, the year/month guidance ('omit for the current month') largely restates the schema text rather than adding new semantics.

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?

Names a specific verb and resource ('Deep link to the Calendar (/calendars)') and immediately characterizes the view: a month grid of scheduled/forecast budget events with a projected daily closing balance. It also explicitly contrasts itself with navigate_to_cashflows and navigate_to_transactions, so an agent can route without opening sibling schemas.

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 an explicit 'pick this for' trigger with four concrete example asks ('what bills are due this month', 'when's my next paycheck', etc.), plus named alternatives with the conditions that select them (aggregate multi-month projection → navigate_to_cashflows; past actuals → navigate_to_transactions). When-to-use, when-not-to-use, and alternatives are all present.

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