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

Annotations already cover safety (readOnlyHint, destructiveHint=false, idempotentHint, openWorldHint), so the description's extra value is the determinism guarantee — it is a local index, never invokes another AI model — plus the empty-result fallback protocol. That is additive behavioral context beyond the annotations, though it says nothing about result richness or latency.

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?

Three sentences, front-loaded with the core action, then the determinism claim, then the fallback. The 'never invokes another AI model' line is short and carries real signal. Nothing is padded, though it is slightly more about system guarantees than about how to call the tool.

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 need no explanation, and the fallback path is documented. Still missing are the parameter contract, expected query format, and whether results are ranked — gaps the 0% schema coverage leaves unfilled.

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% and the description never mentions the two parameters. An agent gets no guidance on what 'query' should contain (place name vs. free text), the minLength=2 constraint, or what 'limit' (default 8, max 20) controls. With zero coverage the description had to compensate and does not.

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 and resource ('searches Sahadeva's deterministic local catalogue and geographic index'), which clearly separates it from the analyze_*/calculate_* astrology siblings. It never explicitly says it returns place coordinates for chart calculation, though the fallback sentence implies it. Clear, but one step short of naming the delivered artifact.

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 a real usage rule: try this first, and if it yields nothing, the MCP host should resolve the place with its own capabilities and pass coordinates to the chart tool. That fallback is genuinely actionable. It stops short of naming the downstream sibling (e.g. calculate_chart_from_known_place) that consumes the coordinates.

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