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

With no annotations, the description carries the full burden. It does disclose the offline-vs-online geocoding split (a real network dependency) and the astrological conventions used (Placidus houses, major aspects, classic orbs), which is valuable. But it omits important behavioral facts: that hour/minute default to 12:00 when birth time is unknown, and what that default implies for house accuracy.

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 tightly written sentences with zero filler, front-loading what the tool returns before explaining how to supply location. The example coordinates make the format concrete without bloat; only the missing time defaults keep it from being fully complete.

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 values needn't be spelled out, and the description nonetheless summarizes them usefully. Given 11 parameters and no annotation safety profile, the remaining gap is the silent 12:00 default for hour/minute and coordinate sign convention, which matter for correctness but are secondary to the well-covered location handling.

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 0% across 11 parameters, so the description must compensate and it only partly does. It clarifies the genuinely ambiguous ones — lng/lat/tz_str with a concrete example ('-74.01, 40.71, America/New_York') and the city/nation geocoding fallback — but leaves name, year/month/day ranges, and the hour/minute defaults (12 and 0) entirely undocumented.

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 the specific verb and resource ('Compute a full natal (birth) chart') and enumerates the exact deliverables: 10 planets with sign/degree/house/retrograde, 12 Placidus cusps, and aspects with orbs. This clearly distinguishes it from the sibling get_current_transits (which would be current/transit positions rather than a birth chart).

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?

The description gives a genuine conditional rule for input modes — pass lng/lat/tz_str for exact offline computation, otherwise city+nation get geocoded online — which is useful decision guidance. However, it says nothing about when to pick this tool over siblings like get_current_transits, nor any prerequisite or exclusion conditions.

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