List Philippine regions

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

Annotations already declare readOnly/idempotent/openWorld, so the safety profile is covered. The description adds value annotations do not: the result set is a fixed, complete set of 17 regions and each row carries four named fields, implying no pagination and exhaustive coverage. It does not discuss auth or rate limits, which is acceptable for a small static reference call.

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 sentences, front-loaded with what is returned, followed by the actionable routing tip. No redundant restatement of the title or 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?

With no output schema, the description compensates by naming the exact fields returned and the universe of results (17 regions). For a simple read-only reference lookup with fully documented parameters and annotations, nothing an agent needs to call it correctly is missing.

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% with documented enums for both island_group and response_format, so the schema carries parameter meaning. The description adds no syntax or behavioral detail about filtering by island group or the effect of response_format, leaving it at the baseline for fully documented schemas.

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 resource with an exact scope ('The 17 regions of the Philippines') and enumerates the returned fields (code, name, island group, regional center) with example code formats (NCR, R10, BARMM). An agent can distinguish this listing tool from ph_list_schools or ph_get_weather without opening the schema.

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 concrete downstream use: 'Use the codes as the region filter in ph_list_schools', which tells the agent when this tool is a prerequisite step. It does not name a distinct alternative to this tool or state exclusions, but no sibling lists regions, so the routing gap is small.

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