combine_btc_psbts

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

The annotations already indicate destructive and idempotent behavior. The description adds significant transparency: it explains the merging logic (combines witness data only), error handling (refuses on body mismatch), return value (merged PSBT plus per-input signature count), and an important behavioral note ('No device touch'). No contradictions with 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 concise (four sentences) and front-loads the main purpose. Every sentence adds unique value: the purpose, input requirements, error behavior, return value, and a notable behavioral trait. No superfluous words.

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 simplicity (one parameter with full schema description, no output schema, and annotations providing safety profile), the description is complete. It explains all necessary aspects: input constraints, merging logic, error behavior, output, and the fact that no device interaction is required. Nothing 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?

There is only one parameter ('psbts') with complete schema description coverage (100%). The schema's own description already details the constraints (2-15 items, base64-encoded PSBT v0, same unsigned tx body). The tool description does not add new parameter-specific information beyond what the schema provides, so a baseline score of 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 the verb ('Merge'), the resource ('partial PSBTs from multi-sig cosigners'), and the specific outcome ('one whose inputs carry every cosigner's signature'). It distinguishes this tool from siblings like 'sign_btc_multisig_psbt' and 'finalize_btc_psbt' by focusing on combining multiple partial PSBTs.

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 strong context for when to use the tool: merging 2-15 base64-encoded PSBT v0 strings that share the same unsigned tx body. It also warns against misuse by stating that it refuses on body mismatch. However, it does not explicitly mention when not to use it compared to alternatives like 'finalize_btc_psbt' or 'sign_btc_multisig_psbt', but the usage scenario is clear.

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