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

Annotations already indicate readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the tool is clearly a safe, read-only, idempotent operation. The description adds useful context about cost ($0.001 per call) and that results are derived from code rather than assumed, which goes beyond the annotations. However, it doesn't detail response structure or error behavior, but that is partially covered by the output schema.

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 concise, with three sentences covering purpose, pricing, and chain list. It is front-loaded with the main purpose. The mention of a byte-identical GET endpoint is useful for debugging but adds a bit of extra length. Overall, every sentence earns its place, though it could be slightly tightened.

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?

The description is complete for an agent to call the tool correctly: it explains what it does, costs, supported chains, and parameter defaults. The output schema is present, so return values are documented elsewhere. Cost and the difference from trusting a README are not in the schema or annotations, making the description cover the needed context.

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%, so the schema already documents all parameters. The description adds context like the default count (40) and max (60) for the count parameter, which is helpful but not critical. The chain parameter's supported values are listed both in the schema description and the tool description, so the description adds limited extra value. Baseline 3 is appropriate.

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 it scans deployed bytecode for 4-byte selectors and identifies named functions. It distinguishes from siblings like chain_bytecode_fingerprint by focusing on function discovery rather than fingerprinting. However, the phrasing 'which functions this code carries' is somewhat colloquial and could be more precise.

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 implies usage when you need to know what functions a contract supports by reading on-chain code, not trusting documentation. It mentions pricing and supported chains, which helps decide when to use it. However, it does not explicitly state when NOT to use it or mention any alternatives.

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