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

Annotations already establish this as a read-only, idempotent, non-destructive, closed-world call, so the safety profile is covered. The description usefully adds that no birth data is required and that results match transits_today, but it never explains what 'tight' means in terms of orbs or what the response contains, which matters more here because there is no output schema.

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?

Two short sentences, front-loaded with the core scope and the elimination of a prerequisite, then the equivalence to a sibling. Nothing is redundant or 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?

With zero required parameters and full schema coverage, the calling contract is clear enough to invoke correctly. The gap is explanatory: 'tight transits' is an undefined qualifier and, absent an output schema, the description does nothing to set expectations about the returned data.

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 all four parameters are already documented in the schema, and the description adds the default-day behavior and the saved-chart framing on top. It does not elaborate on chart_id selection order or timezone precedence beyond what the schema states, so it is modest added value rather than new meaning.

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 verb and resource are concrete: it computes tight transits for a single day against one saved chart belonging to the signed-in user. It also flags 'no birth data needed,' which separates it from birth-data-driven siblings, but it never explicitly contrasts 'my_transits' with 'transits_today' beyond noting identical calculation, leaving the agent to infer which one to pick.

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?

Usage is implied rather than stated: the tool fits when the user references a saved chart and supplies no birth data, and the 'default today' note sets the common case. There is no explicit when-not guidance (e.g., 'use transits_today if the user gives a birth date, or natal_chart for the base chart'), so the agent must reason about the boundary itself.

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