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

Annotations already declare readOnlyHint=true, destructiveHint=false, and idempotentHint=true, so the safety profile is covered. The description adds value by explaining the output structure (grid cells, fishing hours, vessel counts), the data source (GFW AIS-based dataset, 2012–present), and the aggregation granularity (monthly/yearly). It does not detail potential edge cases like large area performance or data gaps, but it adds meaningful behavioral context beyond the 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 four sentences, well-structured, and front-loaded with the primary action. It flows logically from what it does, to output and data source, to use cases, and finally to attribute definition. No redundancy or filler; every sentence earns its place.

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 schema already documents all parameters thoroughly (including the optionality of coordinates and the 12-month range recommendation), the description provides complementary context: output format, aggregation dimensions, and typical use cases. It lacks an explicit statement about pagination or response size handling, but that is not critical for a read-only query tool backed by a well-known dataset. Overall, it is complete enough for an agent to call it correctly.

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 100%; every parameter already has a detailed description including format, constraints, and defaults. The tool description adds only a restatement of the polygon closure requirement and coordinate format, which is already in the schema. It doesn't clarify any ambiguous parameter semantics beyond what the schema provides, so it meets the baseline for well-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?

The description states a clear, specific action: analyze fishing effort intensity across a polygon with specified date range, and explicitly lists the aggregation by gear type and the output format (grid of 0.1-degree cells with fishing hours and vessel counts). This clearly distinguishes it from sibling vessel-level tools (gfw.vessel.*) that focus on individual vessel events or details rather than aggregated effort.

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 clear context on when to use the tool (for marine protected area monitoring, fisheries research, vessel traffic analysis) and implies aggregate analysis versus per-vessel data. However, it does not explicitly name alternative tools or state 'use this instead of X for aggregated effort,' so it falls short of an explicit when/when-not distinction, though it is not misleading.

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