stac_estimate_size

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

With no annotations provided, the description carries the full burden. It discloses that no pixel data is read (only COG headers), making it very fast. It describes the return format (JSON with per-band size details) and provides tips about band size comparisons. While thorough, it does not address error handling or edge cases, which would push it to a 5.

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 well-structured: a one-line summary, followed by Args, Returns, Tips for LLMs, and an Example. Every sentence adds value, and the structure is front-loaded with the core purpose. It is concise yet comprehensive.

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 moderate complexity (4 params, 2 required, no output schema, no annotations), the description is complete. It covers all parameters, return values, use cases, and tips for integration with sibling tools (mosaic, composite). The example rounds out the completeness.

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 0%, so the description must compensate. It explains each parameter: scene_id, bands (with examples), bbox (format and CRS), and output_mode (default and alternatives). The example further clarifies usage. This adds substantial meaning beyond the bare schema.

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's purpose: 'Estimate download size for bands from a scene (no pixel data read).' It specifies reading only COG headers to determine dimensions, dtype, and estimated file size. This distinguishes it from download tools and sibling tools like stac_download_bands.

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 explicit guidance on when to use: 'Use this before large downloads to understand how much data will be transferred.' Tips for LLMs further instruct: 'Call this BEFORE large downloads to check feasibility' and recommend actions if estimated_mb > 500. It also mentions planning for stac_mosaic or stac_temporal_composite, offering context for alternatives.

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