postbag

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postbag_read

Read-onlyIdempotent

Read recent letters from a bag in chronological order, excluding endpoint credentials. Page backward with before set to the last ledger record number.

Instructions

Read recent records in chronological order, excluding endpoint credentials.

Pass next_before as before to page backward by ledger record number. The letters count covers the whole bag. Peer registration is not liveness.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "postbag_read"
  }
}

Input Schema

Name	Required	Description	Default
`bag`	No	Default or named bag. Join creates a missing bag.	default
`limit`	No
`before`	No

Output Schema

Name	Required	Description	Default
`ok`	Yes
`data`	Yes
`message`	Yes
`error_code`	Yes
`submission_state`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.2.0Oct 2, 2026

TDQS

A3.5/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds genuine context beyond that: results are chronological, endpoint credentials are withheld, paging moves backward by ledger record number, and the 'peer registration is not liveness' caveat warns against over-reading presence data.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

It is short and front-loads the core read semantics, but reads like leftover notes: sentences are disconnected fragments, and 'the letters count covers the whole bag' and 'Peer registration is not liveness' are cryptic rather than informative.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need not be described, and the description does cover ordering, credential exclusion and paging. However, with no required parameters and a partially documented schema, the unexplained 'limit' parameter and jargon-heavy caveats leave the definition adequate rather than complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 33% (only 'bag' is documented). The description compensates for 'before' by explaining backward paging via the ledger number, but leaves 'limit' unexplained and does not clarify its 1-100 bound or how it interacts with paging.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The opening sentence gives a specific verb+resource (read records, chronological order) and names a scope constraint (excluding endpoint credentials). It does not, however, differentiate itself from siblings like postbag_bags or postbag_send, and the surrounding jargon ('ledger record number', 'the letters count') adds ambiguity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description supplies real paging guidance ('Pass next_before as before to page backward'), which tells the agent how to traverse results. But it never states when to use postbag_read versus postbag_bags or the other siblings, and gives no preconditions for calling it.

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

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