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

Annotations declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the safety profile is already clear. The description adds value by disclosing that queries are 'honest' regarding horizon (lat=44 constraint) and includes cultural sensitivity guidance ('Never "the Indians"'). These go beyond annotations.

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?

The description is two sentences long and front-loads the purpose. The first sentence is dense but clear; the second provides quick examples. Slightly more context could be added without verbosity, but it's efficient.

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?

Given the tool's complexity (8 params, cultural sensitivity), the description covers key usage patterns and behavioral nuance well. There is an output schema, so return format details are handled. The description doesn't explain how queries combine parameters or how the horizon honesty constraint works, but it's sufficient for most uses.

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 low at 38%, but the description provides concrete examples of how to use common parameters (q, nation, western, theme, lat). It adds meaning beyond the schema for some parameters, but doesn't cover all 8 parameters (e.g., lang, lng/lon aliases are not mentioned). Baseline adjusted for low coverage, but still only partial compensation.

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 description clearly states the tool queries 'Ciel des peuples' and lists what it returns (nations, asterisms with RA/Dec, sources, etc.). It's a specific verb-resource combination, but doesn't explicitly distinguish it from siblings like 'object_lookup' or 'asterisms', which is a minor gap.

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 provides examples of query parameters (e.g., 'nation=dine', 'q=pléiades') which imply usage, but doesn't explicitly state when to use this tool versus alternatives like 'object_lookup' or 'tonight_sky'. No when-not-to-use guidance is given.

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